diff --git a/extra/L-system/L-system.factor b/extra/L-system/L-system.factor
new file mode 100644
index 0000000000..97a971de47
--- /dev/null
+++ b/extra/L-system/L-system.factor
@@ -0,0 +1,448 @@
+
+USING: accessors arrays assocs colors combinators.short-circuit
+kernel locals math math.functions math.matrices math.order
+math.parser math.trig math.vectors opengl opengl.demo-support
+opengl.gl sbufs sequences strings ui.gadgets ui.gadgets.worlds
+ui.gestures ui.render ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+IN: L-system
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+TUPLE: <turtle> pos ori angle length thickness color vertices saved ;
+
+DEFER: default-L-parser-values
+
+: reset-turtle ( turtle -- turtle )
+  { 0 0 0 } clone   >>pos
+  3 identity-matrix >>ori
+  V{ } clone >>vertices
+  V{ } clone >>saved
+
+  default-L-parser-values ;
+
+: turtle ( -- turtle ) <turtle> new reset-turtle ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+:: step-turtle ( TURTLE LENGTH -- turtle )
+
+  TURTLE
+    TURTLE pos>>   TURTLE ori>> { 0 0 LENGTH } m.v   v+
+  >>pos ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+:: Rx ( ANGLE -- Rx )
+  
+  [let | ANGLE [ ANGLE deg>rad ] |
+
+    [let | A [ ANGLE cos     ]
+           B [ ANGLE sin neg ]
+           C [ ANGLE sin     ]
+           D [ ANGLE cos     ] |
+
+      { { 1 0 0 }
+        { 0 A B }
+        { 0 C D } }
+
+    ] ] ;
+
+:: Ry ( ANGLE -- Ry )
+  
+  [let | ANGLE [ ANGLE deg>rad ] |
+
+    [let | A [ ANGLE cos     ]
+           B [ ANGLE sin     ]
+           C [ ANGLE sin neg ]
+           D [ ANGLE cos     ] |
+
+      { { A 0 B }
+        { 0 1 0 }
+        { C 0 D } }
+
+    ] ] ;
+
+:: Rz ( ANGLE -- Rz )
+  
+  [let | ANGLE [ ANGLE deg>rad ] |
+
+    [let | A [ ANGLE cos     ]
+           B [ ANGLE sin neg ]
+           C [ ANGLE sin     ]
+           D [ ANGLE cos     ] |
+
+      { { A B 0 }
+        { C D 0 }
+        { 0 0 1 } }
+
+    ] ] ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+:: apply-rotation ( TURTLE ROTATION -- turtle )
+  
+  TURTLE  TURTLE ori>> ROTATION m.  >>ori ;
+
+: rotate-x ( turtle angle -- turtle ) Rx apply-rotation ;
+: rotate-y ( turtle angle -- turtle ) Ry apply-rotation ;
+: rotate-z ( turtle angle -- turtle ) Rz apply-rotation ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+: pitch-up   ( turtle angle -- turtle ) neg rotate-x ;
+: pitch-down ( turtle angle -- turtle )     rotate-x ;
+
+: turn-left  ( turtle angle -- turtle )     rotate-y ;
+: turn-right ( turtle angle -- turtle ) neg rotate-y ;
+
+: roll-left  ( turtle angle -- turtle ) neg rotate-z ;
+: roll-right ( turtle angle -- turtle )     rotate-z ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+: V ( -- V ) { 0 1 0 } ;
+
+: X ( turtle -- 3array ) ori>> [ first  ] map ;
+: Y ( turtle -- 3array ) ori>> [ second ] map ;
+: Z ( turtle -- 3array ) ori>> [ third  ] map ;
+
+: set-X ( turtle seq -- turtle ) over ori>> [ set-first  ] 2each ;
+: set-Y ( turtle seq -- turtle ) over ori>> [ set-second ] 2each ;
+: set-Z ( turtle seq -- turtle ) over ori>> [ set-third  ] 2each ;
+
+:: roll-until-horizontal ( TURTLE -- turtle )
+
+  TURTLE
+  
+    V         TURTLE Z  cross normalize  set-X
+
+    TURTLE Z  TURTLE X  cross normalize  set-Y ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+:: strafe-up ( TURTLE LENGTH -- turtle )
+  TURTLE 90 pitch-up LENGTH step-turtle 90 pitch-down ;
+
+:: strafe-down ( TURTLE LENGTH -- turtle )
+  TURTLE 90 pitch-down LENGTH step-turtle 90 pitch-up ;
+
+:: strafe-left ( TURTLE LENGTH -- turtle )
+  TURTLE 90 turn-left LENGTH step-turtle 90 turn-right ;
+
+:: strafe-right ( TURTLE LENGTH -- turtle )
+  TURTLE 90 turn-right LENGTH step-turtle 90 turn-left ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+: polygon ( vertices -- ) GL_POLYGON glBegin [ first3 glVertex3d ] each glEnd ;
+
+: start-polygon ( turtle -- turtle ) dup vertices>> delete-all ;
+
+: finish-polygon ( turtle -- turtle ) dup vertices>> polygon ;
+
+: polygon-vertex ( turtle -- turtle ) dup [ pos>> ] [ vertices>> ] bi push ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+: record-vertex ( turtle -- turtle ) dup pos>> first3 glVertex3d ;
+
+: draw-forward ( turtle length -- turtle )
+  GL_LINES glBegin [ record-vertex ] dip step-turtle record-vertex glEnd ;
+
+: move-forward ( turtle length -- turtle ) step-turtle polygon-vertex ;
+
+: sneak-forward ( turtle length -- turtle ) step-turtle ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+: scale-length ( turtle m -- turtle ) over length>> * >>length ;
+: scale-angle  ( turtle m -- turtle ) over angle>>  * >>angle  ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+: set-thickness ( turtle i -- turtle ) dup glLineWidth >>thickness ;
+
+: scale-thickness ( turtle m -- turtle )
+  over thickness>> * 0.5 max set-thickness ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+: color-table ( -- colors )
+  {
+    T{ rgba f 0    0    0    1 } ! black
+    T{ rgba f 0.5  0.5  0.5  1 } ! grey
+    T{ rgba f 1    0    0    1 } ! red
+    T{ rgba f 1    1    0    1 } ! yellow
+    T{ rgba f 0    1    0    1 } ! green
+    T{ rgba f 0.25 0.88 0.82 1 } ! turquoise
+    T{ rgba f 0    0    1    1 } ! blue
+    T{ rgba f 0.63 0.13 0.94 1 } ! purple
+    T{ rgba f 0.00 0.50 0.00 1 } ! dark green
+    T{ rgba f 0.00 0.82 0.82 1 } ! dark turquoise
+    T{ rgba f 0.00 0.00 0.50 1 } ! dark blue
+    T{ rgba f 0.58 0.00 0.82 1 } ! dark purple
+    T{ rgba f 0.50 0.00 0.00 1 } ! dark red
+    T{ rgba f 0.25 0.25 0.25 1 } ! dark grey
+    T{ rgba f 0.75 0.75 0.75 1 } ! medium grey
+    T{ rgba f 1    1    1    1 } ! white
+  } ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+! : material-color ( color -- )
+!   GL_FRONT_AND_BACK GL_AMBIENT_AND_DIFFUSE rot gl-material ;
+
+: material-color ( color -- )
+  GL_FRONT_AND_BACK GL_AMBIENT_AND_DIFFUSE rot color>raw 4array gl-material ;
+
+: set-color ( turtle i -- turtle )
+  dup color-table nth dup gl-color material-color >>color ;
+
+: inc-color ( turtle -- turtle ) dup color>> 1 + set-color ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+: save-turtle    ( turtle -- turtle ) dup clone over saved>> push ;
+: restore-turtle ( turtle -- turtle )                saved>> pop  ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+: default-L-parser-values ( turtle -- turtle )
+  1 >>length 45 >>angle 1 >>thickness 2 >>color ;
+
+: L-parser-dialect ( -- commands )
+
+  {
+      { "+" [ dup angle>> turn-left  ] }
+      { "-" [ dup angle>> turn-right ] }
+      { "&" [ dup angle>> pitch-down ] }
+      { "^" [ dup angle>> pitch-up   ] }
+      { "<" [ dup angle>> roll-left  ] }
+      { ">" [ dup angle>> roll-right ] }
+
+      { "|" [ 180.0         rotate-y ] }
+      { "%" [ 180.0         rotate-z ] }
+      { "$" [ roll-until-horizontal  ]  }
+
+      { "F" [ dup length>>     draw-forward  ] }
+      { "Z" [ dup length>> 2 / draw-forward  ] }
+      { "f" [ dup length>>     move-forward  ] }
+      { "z" [ dup length>> 2 / move-forward  ] }
+      { "g" [ dup length>>     sneak-forward ] }
+      { "." [ polygon-vertex                 ] }
+
+      { "[" [ save-turtle      ] }
+      { "]" [ restore-turtle   ] }
+      
+      { "{" [ start-polygon    ] }
+      { "}" [ finish-polygon   ] }
+
+      { "/" [ 1.1 scale-length    ] } ! double quote command in lparser
+      { "'" [ 0.9 scale-length    ] }
+      { ";" [ 1.1 scale-angle     ] }
+      { ":" [ 0.9 scale-angle     ] }
+      { "?" [ 1.4 scale-thickness ] }
+      { "!" [ 0.7 scale-thickness ] }
+
+      { "c" [ dup color>> 1 + color-table length mod set-color ] }
+
+    }
+    ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+TUPLE: <L-system> < gadget
+  camera display-list
+  commands axiom rules string ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+: open-paren  ( -- ch ) CHAR: ( ;
+: close-paren ( -- ch ) CHAR: ) ;
+
+: open-paren?  ( obj -- ? ) open-paren  = ;
+: close-paren? ( obj -- ? ) close-paren = ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+:: read-instruction ( STRING -- next rest )
+  
+  { [ STRING length 1 > ] [ STRING second open-paren? ] } 0&&
+    [ STRING  close-paren STRING index 1 + cut ]
+    [ STRING  1                            cut ]
+  if ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+:: iterate-string-loop ( STRING RULES ACCUM -- )
+  STRING empty? not
+    [
+      STRING read-instruction
+    
+      [let | REST [ ] NEXT [ ] |
+
+        NEXT 1 head RULES at  NEXT  or  ACCUM push-all
+
+        REST RULES ACCUM iterate-string-loop ]
+    ]
+  when ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+:: iterate-string ( STRING RULES -- string )
+
+  [let | ACCUM [ STRING length  10 *  <sbuf> ] |
+
+    STRING RULES ACCUM iterate-string-loop
+
+    ACCUM >string ] ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+:: interpret-string ( STRING COMMANDS -- )
+
+  STRING empty? not
+    [
+      STRING read-instruction
+
+      [let | REST [ ] NEXT [ ] |
+
+        [let | COMMAND [ NEXT 1 head COMMANDS at ] |
+
+          COMMAND
+            [
+              NEXT length 1 =
+                [ COMMAND call ]
+                [
+                  NEXT 2 tail 1 head* string>number
+                  COMMAND 1 tail*
+                  call
+                ]
+              if
+            ]
+          when ]
+
+        REST COMMANDS interpret-string ]
+    ]
+  when ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+:: iterate-L-system-string ( L-SYSTEM -- )
+  L-SYSTEM string>>
+  L-SYSTEM rules>>
+  iterate-string
+  L-SYSTEM (>>string) ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+:: do-camera-look-at ( CAMERA -- )
+
+  [let | EYE   [ CAMERA pos>> ]
+         FOCUS [ CAMERA clone 1 step-turtle pos>> ]
+         UP    [ CAMERA clone 90 pitch-up 1 step-turtle pos>> CAMERA pos>> v- ]
+       |
+
+    EYE FOCUS UP gl-look-at ] ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+:: generate-display-list ( L-SYSTEM -- )
+
+  L-SYSTEM find-gl-context
+
+  L-SYSTEM display-list>> GL_COMPILE glNewList
+
+    turtle
+    L-SYSTEM string>>
+    L-SYSTEM commands>>
+    interpret-string
+    drop
+
+  glEndList ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+M:: <L-system> draw-gadget* ( L-SYSTEM -- )
+
+  black gl-clear
+
+  GL_FLAT glShadeModel
+
+  GL_PROJECTION glMatrixMode
+  glLoadIdentity
+  -1 1 -1 1 1.5 200 glFrustum
+
+  GL_MODELVIEW glMatrixMode
+
+  glLoadIdentity
+
+  L-SYSTEM camera>> do-camera-look-at
+
+  GL_FRONT_AND_BACK GL_LINE glPolygonMode
+
+  ! draw axis
+  white gl-color GL_LINES glBegin { 0 0 0 } gl-vertex { 0 0 1 } gl-vertex glEnd
+
+  L-SYSTEM display-list>> glCallList ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+M:: <L-system> graft* ( L-SYSTEM -- )
+
+  L-SYSTEM find-gl-context
+
+  1 glGenLists L-SYSTEM (>>display-list) ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+M:: <L-system> pref-dim* ( L-SYSTEM -- dim ) { 400 400 } ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+:: camera-left ( L-SYSTEM -- )
+  L-SYSTEM camera>> 5 turn-left drop
+  L-SYSTEM relayout-1 ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+:: with-camera ( L-SYSTEM QUOT -- )
+  L-SYSTEM camera>> QUOT call drop
+  L-SYSTEM relayout-1 ;
+
+<L-system>
+H{
+  { T{ key-down f f "LEFT"  } [ [  5 turn-left   ] with-camera ] }
+  { T{ key-down f f "RIGHT" } [ [  5 turn-right  ] with-camera ] }
+  { T{ key-down f f "UP"    } [ [  5 pitch-down  ] with-camera ] }
+  { T{ key-down f f "DOWN"  } [ [  5 pitch-up    ] with-camera ] }
+  
+  { T{ key-down f f "a"     } [ [  1 step-turtle ] with-camera ] }
+  { T{ key-down f f "z"     } [ [ -1 step-turtle ] with-camera ] }
+
+  {
+    T{ key-down f f "x" }
+    [
+      dup iterate-L-system-string
+      dup generate-display-list
+      dup relayout-1
+      drop
+    ]
+  }
+    
+}
+set-gestures
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+: L-system ( -- L-system )
+
+  <L-system> new-gadget
+  
+    turtle 45 turn-left 45 pitch-up 5 step-turtle 180 turn-left >>camera ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
diff --git a/extra/L-system/models/abop-1/abop-1.factor b/extra/L-system/models/abop-1/abop-1.factor
new file mode 100644
index 0000000000..45cc522470
--- /dev/null
+++ b/extra/L-system/models/abop-1/abop-1.factor
@@ -0,0 +1,29 @@
+
+USING: accessors kernel ui L-system ;
+
+IN: L-system.models.abop-1
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+: abop-1 ( <L-system> -- <L-system> )
+  
+  L-parser-dialect >>commands
+
+  "c(12)FFAL" >>axiom
+
+  {
+    { "A" "F[&'(.8)!BL]>(137)'!(.9)A"   }
+    { "B" "F[-'(.8)!(.9)$CL]'!(.9)C"    }
+    { "C" "F[+'(.8)!(.9)$BL]'!(.9)B"    }
+    
+    { "L" "~c(8){+(30)f-(120)f-(120)f}" }
+  }
+  >>rules
+
+  dup axiom>> >>string ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+: main ( -- ) [ L-system abop-1 "L-system" open-window ] with-ui ;
+
+MAIN: main
diff --git a/extra/fuel/fuel.factor b/extra/fuel/fuel.factor
index 7f6af22df8..80d8cde654 100644
--- a/extra/fuel/fuel.factor
+++ b/extra/fuel/fuel.factor
@@ -1,11 +1,12 @@
-! Copyright (C) 2008 Jose Antonio Ortega Ruiz.
+! Copyright (C) 2008, 2009 Jose Antonio Ortega Ruiz.
 ! See http://factorcode.org/license.txt for BSD license.
 
 USING: accessors arrays assocs classes.tuple combinators
-compiler.units continuations debugger definitions io io.pathnames
-io.streams.string kernel lexer math math.order memoize namespaces
-parser prettyprint sequences sets sorting source-files strings summary
-tools.vocabs vectors vocabs vocabs.parser words ;
+compiler.units continuations debugger definitions help help.crossref
+help.markup help.topics io io.pathnames io.streams.string kernel lexer
+make math math.order memoize namespaces parser prettyprint sequences
+sets sorting source-files strings summary tools.crossref tools.vocabs
+vectors vocabs vocabs.parser words ;
 
 IN: fuel
 
@@ -17,13 +18,13 @@ SYMBOL: fuel-status-stack
 V{ } clone fuel-status-stack set-global
 
 SYMBOL: fuel-eval-result
-f clone fuel-eval-result set-global
+f fuel-eval-result set-global
 
 SYMBOL: fuel-eval-output
-f clone fuel-eval-result set-global
+f fuel-eval-result set-global
 
 SYMBOL: fuel-eval-res-flag
-t clone fuel-eval-res-flag set-global
+t fuel-eval-res-flag set-global
 
 : fuel-eval-restartable? ( -- ? )
     fuel-eval-res-flag get-global ; inline
@@ -56,6 +57,12 @@ GENERIC: fuel-pprint ( obj -- )
 
 M: object fuel-pprint pprint ; inline
 
+: fuel-maybe-scape ( ch -- seq )
+    dup "\\\"?#()[]'`" member? [ CHAR: \ swap 2array ] [ 1array ] if ;
+
+M: word fuel-pprint
+    name>> V{ } clone [ fuel-maybe-scape append ] reduce >string write ;
+
 M: f fuel-pprint drop "nil" write ; inline
 
 M: integer fuel-pprint pprint ; inline
@@ -105,12 +112,11 @@ M: source-file fuel-pprint path>> fuel-pprint ;
 : fuel-forget-error ( -- ) f error set-global ; inline
 : fuel-forget-result ( -- ) f fuel-eval-result set-global ; inline
 : fuel-forget-output ( -- ) f fuel-eval-output set-global ; inline
+: fuel-forget-status ( -- )
+    fuel-forget-error fuel-forget-result fuel-forget-output ; inline
 
 : (fuel-begin-eval) ( -- )
-    fuel-push-status
-    fuel-forget-error
-    fuel-forget-result
-    fuel-forget-output ;
+    fuel-push-status fuel-forget-status ; inline
 
 : (fuel-end-eval) ( output -- )
     fuel-eval-output set-global fuel-retort fuel-pop-status ; inline
@@ -136,14 +142,17 @@ M: source-file fuel-pprint path>> fuel-pprint ;
 
 ! Loading files
 
-: fuel-run-file ( path -- ) run-file ; inline
+SYMBOL: :uses
 
-: fuel-with-autouse ( quot -- )
-    [
-        auto-use? on
-        [ amended-use get clone fuel-eval-set-result ] print-use-hook set
-        call
-    ] curry with-scope ;
+: fuel-set-use-hook ( -- )
+    [ amended-use get clone :uses prefix fuel-eval-set-result ]
+    print-use-hook set ;
+
+: fuel-run-file ( path -- )
+    [ fuel-set-use-hook run-file ] curry with-scope ; inline
+
+: fuel-with-autouse ( ... quot: ( ... -- ... ) -- ... )
+    [ auto-use? on fuel-set-use-hook call ] curry with-scope ; inline
 
 : (fuel-get-uses) ( lines -- )
     [ parse-fresh drop ] curry with-compilation-unit ; inline
@@ -175,13 +184,16 @@ M: source-file fuel-pprint path>> fuel-pprint ;
     [ [ first ] dip first <=> ] sort ; inline
 
 : fuel-format-xrefs ( seq -- seq' )
-    [ word? ] filter [ fuel-word>xref ] map fuel-sort-xrefs ;
+    [ word? ] filter [ fuel-word>xref ] map ; inline
 
 : fuel-callers-xref ( word -- )
-    usage fuel-format-xrefs fuel-eval-set-result ; inline
+    usage fuel-format-xrefs fuel-sort-xrefs fuel-eval-set-result ; inline
 
 : fuel-callees-xref ( word -- )
-    uses fuel-format-xrefs fuel-eval-set-result ; inline
+    uses fuel-format-xrefs fuel-sort-xrefs fuel-eval-set-result ; inline
+
+: fuel-apropos-xref ( str -- )
+    words-matching fuel-format-xrefs fuel-eval-set-result ; inline
 
 ! Completion support
 
@@ -216,6 +228,86 @@ MEMO: (fuel-vocab-words) ( name -- seq )
 : fuel-get-words ( prefix names -- )
     (fuel-get-words) fuel-eval-set-result ; inline
 
+! Help support
+
+MEMO: fuel-articles-seq ( -- seq )
+    articles get values ;
+
+: fuel-find-articles ( title -- seq )
+    [ [ article-title ] dip = ] curry fuel-articles-seq swap filter ;
+
+MEMO: fuel-find-article ( title -- article/f )
+    fuel-find-articles dup empty? [ drop f ] [ first ] if ;
+
+MEMO: fuel-article-title ( name -- title/f )
+    articles get at [ article-title ] [ f ] if* ;
+
+: fuel-get-article ( name -- )
+    article fuel-eval-set-result ;
+
+: fuel-value-str ( word -- str )
+    [ pprint-short ] with-string-writer ; inline
+
+: fuel-definition-str ( word -- str )
+    [ see ] with-string-writer ; inline
+
+: fuel-methods-str ( word -- str )
+    methods dup empty? not [
+        [ [ see nl ] each ] with-string-writer
+    ] [ drop f ] if ; inline
+
+: fuel-related-words ( word -- seq )
+    dup "related" word-prop remove ; inline
+
+: fuel-parent-topics ( word -- seq )
+    help-path [ dup article-title swap 2array ] map ; inline
+
+: (fuel-word-help) ( word -- element )
+    dup \ article swap article-title rot
+    [
+        {
+            [ fuel-parent-topics [ \ $doc-path prefix , ] unless-empty ]
+            [ \ $vocabulary swap vocabulary>> 2array , ]
+            [ word-help % ]
+            [ fuel-related-words [ \ $related swap 2array , ] unless-empty ]
+            [ get-global [ \ $value swap fuel-value-str 2array , ] when* ]
+            [ \ $definition swap fuel-definition-str 2array , ]
+            [ fuel-methods-str [ \ $methods swap 2array , ] when* ]
+        } cleave
+    ] { } make 3array ;
+
+MEMO: fuel-find-word ( name -- word/f )
+    [ [ name>> ] dip = ] curry all-words swap filter
+    dup empty? not [ first ] [ drop f ] if ;
+
+: fuel-word-help ( name -- )
+    fuel-find-word [ [ auto-use? on (fuel-word-help) ] with-scope ] [ f ] if*
+    fuel-eval-set-result ; inline
+
+: (fuel-word-see) ( word -- elem )
+    [ name>> \ article swap ]
+    [ [ see ] with-string-writer \ $code swap 2array ] bi 3array ; inline
+
+: fuel-word-see ( name -- )
+    fuel-find-word [ [ auto-use? on (fuel-word-see) ] with-scope ] [ f ] if*
+    fuel-eval-set-result ; inline
+
+: (fuel-vocab-help) ( name -- element )
+    \ article swap dup >vocab-link
+    [
+        [ summary [ , ] [ "No summary available" , ] if* ]
+        [ drop \ $nl , ]
+        [ vocab-help article [ content>> % ] when* ] tri
+    ] { } make 3array ;
+
+: fuel-vocab-help ( name -- )
+    (fuel-vocab-help) fuel-eval-set-result ; inline
+
+: (fuel-index) ( seq -- seq )
+    [ [ >link name>> ] [ article-title ] bi 2array \ $subsection prefix ] map ;
+
+: fuel-index ( quot: ( -- seq ) -- )
+    call (fuel-index) fuel-eval-set-result ; inline
 
 ! -run=fuel support
 
diff --git a/misc/fuel/README b/misc/fuel/README
index b670eef84d..6c03c7aa01 100644
--- a/misc/fuel/README
+++ b/misc/fuel/README
@@ -1,108 +1,115 @@
-FUEL, Factor's Ultimate Emacs Library
+FUEL, Factor's Ultimate Emacs Library                              -*- org -*-
 -------------------------------------
 
 FUEL provides a complete environment for your Factor coding pleasure
 inside Emacs, including source code edition and interaction with a
 Factor listener instance running within Emacs.
 
-FUEL was started by Jose A Ortega as an extension to Ed Cavazos'
-original factor.el code.
+FUEL was started by Jose A Ortega as an extension to Eduardo Cavazos'
+original factor.el code. Eduardo is also responsible of naming the
+beast.
 
-Installation
-------------
+* Installation
 
-FUEL comes bundled with Factor's distribution. The folder misc/fuel
-contains Elisp code, and there's a fuel vocabulary in extras/fuel.
+  FUEL comes bundled with Factor's distribution. The folder misc/fuel
+  contains Elisp code, and there's a fuel vocabulary in extras/fuel.
 
-To install FUEL, either add this line to your Emacs initialisation:
+  To install FUEL, either add this line to your Emacs initialisation:
 
   (load-file "<path/to/factor/installation>/misc/fuel/fu.el")
 
-or
+  or
 
   (add-to-list load-path "<path/to/factor/installation>/fuel")
   (require 'fuel)
 
-If all you want is a major mode for editing Factor code with pretty
-font colors and indentation, without running the factor listener
-inside Emacs, you can use instead:
+  If all you want is a major mode for editing Factor code with pretty
+  font colors and indentation, without running the factor listener
+  inside Emacs, you can use instead:
 
   (add-to-list load-path "<path/to/factor/installation>/fuel")
   (setq factor-mode-use-fuel nil)
   (require 'factor-mode)
 
-Basic usage
------------
+* Basic usage
 
-If you're using the default factor binary and images locations inside
-the Factor's source tree, that should be enough to start using FUEL.
-Editing any file with the extension .factor will put you in
-factor-mode; try C-hm for a summary of available commands.
+  If you're using the default factor binary and images locations inside
+  the Factor's source tree, that should be enough to start using FUEL.
+  Editing any file with the extension .factor will put you in
+  factor-mode; try C-hm for a summary of available commands.
 
-To start the listener, try M-x run-factor.
+  To start the listener, try M-x run-factor.
 
-Many aspects of the environment can be customized:
-M-x customize-group fuel will show you how many.
+  Many aspects of the environment can be customized:
+  M-x customize-group fuel will show you how many.
 
-Quick key reference
--------------------
+* Quick key reference
 
-(Triple chords ending in a single letter <x> accept also C-<x> (e.g.
-C-cC-eC-r is the same as C-cC-er)).
+  (Triple chords ending in a single letter <x> accept also C-<x> (e.g.
+  C-cC-eC-r is the same as C-cC-er)).
 
-* In factor source files:
+*** In factor source files:
 
- - C-cz : switch to listener
- - C-co : cycle between code, tests and docs factor files
+    - C-cz : switch to listener
+    - C-co : cycle between code, tests and docs factor files
 
- - M-. : edit word at point in Emacs
- - M-TAB : complete word at point
- - C-cC-eu : update USING: line
- - C-cC-ev : edit vocabulary (M-x fuel-edit-vocabulary)
- - C-cC-ew : edit word (M-x fuel-edit-word-at-point)
- - C-cC-ed : edit word's doc (M-x fuel-edit-word-at-point)
+    - M-. : edit word at point in Emacs
+    - M-TAB : complete word at point
+    - C-cC-eu : update USING: line
+    - C-cC-ev : edit vocabulary (M-x fuel-edit-vocabulary)
+    - C-cC-ew : edit word (M-x fuel-edit-word-at-point)
+    - C-cC-ed : edit word's doc (M-x fuel-edit-word-at-point)
 
- - C-cr, C-cC-er : eval region
- - C-M-r, C-cC-ee : eval region, extending it to definition boundaries
- - C-M-x, C-cC-ex : eval definition around point
- - C-ck, C-cC-ek : run file
+    - C-cr, C-cC-er : eval region
+    - C-M-r, C-cC-ee : eval region, extending it to definition boundaries
+    - C-M-x, C-cC-ex : eval definition around point
+    - C-ck, C-cC-ek : run file
 
- - C-cC-da : toggle autodoc mode
- - C-cC-dd : help for word at point
- - C-cC-ds : short help word at point
- - C-cC-de : show stack effect of current sexp (with prefix, region)
+    - C-cC-da : toggle autodoc mode
+    - C-cC-dd : help for word at point
+    - C-cC-ds : short help word at point
+    - C-cC-de : show stack effect of current sexp (with prefix, region)
+    - C-cC-dp : find words containing given substring (M-x fuel-apropos)
 
- - C-cM-<, C-cC-d< : show callers of word at point
- - C-cM->, C-cC-d> : show callees of word at point
+    - C-cM-<, C-cC-d< : show callers of word at point
+    - C-cM->, C-cC-d> : show callees of word at point
 
-* In the listener:
+*** In the listener:
 
- - TAB : complete word at point
- - M-. : edit word at point in Emacs
- - C-ca : toggle autodoc mode
- - C-cs : toggle stack mode
- - C-cv : edit vocabulary
- - C-ch : help for word at point
- - C-ck : run file
+    - TAB : complete word at point
+    - M-. : edit word at point in Emacs
+    - C-ca : toggle autodoc mode
+    - C-cp : find words containing given substring (M-x fuel-apropos)
+    - C-cs : toggle stack mode
+    - C-cv : edit vocabulary
+    - C-ch : help for word at point
+    - C-ck : run file
 
-* In the debugger (it pops up upon eval/compilation errors):
+*** In the debugger (it pops up upon eval/compilation errors):
 
- - g : go to error
- - <digit> : invoke nth restart
- - w/e/l : invoke :warnings, :errors, :linkage
- - q : bury buffer
+    - g : go to error
+    - <digit> : invoke nth restart
+    - w/e/l : invoke :warnings, :errors, :linkage
+    - q : bury buffer
 
-* In the Help browser:
+*** In the help browser:
 
- - RET : help for word at point
- - f/b : next/previous page
- - SPC/S-SPC : scroll up/down
- - TAB/S-TAB : next/previous headline
- - C-cz : switch to listener
- - q : bury buffer
+    - h : help for word at point
+    - a : find words containing given substring (M-x fuel-apropos)
+    - ba : bookmark current page
+    - bb : display bookmarks
+    - bd : delete bookmark at point
+    - n/p : next/previous page
+    - SPC/S-SPC : scroll up/down
+    - TAB/S-TAB : next/previous link
+    - r : refresh page
+    - c : clean browsing history
+    - M-. : edit word at point in Emacs
+    - C-cz : switch to listener
+    - q : bury buffer
 
-* In crossref buffers
+*** In crossref buffers
 
- - TAB/BACKTAB : navigate links
- - RET/mouse click : follow link
- - q : bury buffer
+    - TAB/BACKTAB : navigate links
+    - RET/mouse click : follow link
+    - q : bury buffer
diff --git a/misc/fuel/fuel-autodoc.el b/misc/fuel/fuel-autodoc.el
index a1c1d19b98..53b5228965 100644
--- a/misc/fuel/fuel-autodoc.el
+++ b/misc/fuel/fuel-autodoc.el
@@ -1,6 +1,6 @@
 ;;; fuel-autodoc.el -- doc snippets in the echo area
 
-;; Copyright (C) 2008 Jose Antonio Ortega Ruiz
+;; Copyright (C) 2008, 2009 Jose Antonio Ortega Ruiz
 ;; See http://factorcode.org/license.txt for BSD license.
 
 ;; Author: Jose Antonio Ortega Ruiz <jao@gnu.org>
@@ -31,22 +31,11 @@
   :group 'fuel-autodoc
   :type 'boolean)
 
+
 
-;;; Autodoc mode:
+;;; Eldoc function:
 
-(defvar fuel-autodoc--font-lock-buffer
-  (let ((buffer (get-buffer-create " *fuel help minibuffer messages*")))
-    (set-buffer buffer)
-    (set-syntax-table fuel-syntax--syntax-table)
-    (fuel-font-lock--font-lock-setup)
-    buffer))
-
-(defun fuel-autodoc--font-lock-str (str)
-  (set-buffer fuel-autodoc--font-lock-buffer)
-  (erase-buffer)
-  (insert str)
-  (let ((font-lock-verbose nil)) (font-lock-fontify-buffer))
-  (buffer-string))
+(defvar fuel-autodoc--timeout 200)
 
 (defun fuel-autodoc--word-synopsis (&optional word)
   (let ((word (or word (fuel-syntax-symbol-at-point)))
@@ -55,11 +44,11 @@
       (let* ((cmd (if (fuel-syntax--in-using)
                       `(:fuel* (,word fuel-vocab-summary) :in t)
                     `(:fuel* (((:quote ,word) synopsis :get)) :in)))
-             (ret (fuel-eval--send/wait cmd 20))
+             (ret (fuel-eval--send/wait cmd fuel-autodoc--timeout))
              (res (fuel-eval--retort-result ret)))
         (when (and ret (not (fuel-eval--retort-error ret)) (stringp res))
           (if fuel-autodoc-minibuffer-font-lock
-              (fuel-autodoc--font-lock-str res)
+              (fuel-font-lock--factor-str res)
             res))))))
 
 (make-variable-buffer-local
@@ -70,6 +59,9 @@
            (funcall fuel-autodoc--fallback-function))
       (fuel-autodoc--word-synopsis)))
 
+
+;;; Autodoc mode:
+
 (make-variable-buffer-local
  (defvar fuel-autodoc-mode-string " A"
    "Modeline indicator for fuel-autodoc-mode"))
diff --git a/misc/fuel/fuel-debug-uses.el b/misc/fuel/fuel-debug-uses.el
index 127e11d23e..7b90093c21 100644
--- a/misc/fuel/fuel-debug-uses.el
+++ b/misc/fuel/fuel-debug-uses.el
@@ -23,12 +23,6 @@
 
 ;;; Customization:
 
-(fuel-font-lock--defface fuel-font-lock-debug-missing-vocab
-  'font-lock-warning-face fuel-debug "missing vocabulary names")
-
-(fuel-font-lock--defface fuel-font-lock-debug-unneeded-vocab
-  'font-lock-warning-face fuel-debug "unneeded vocabulary names")
-
 (fuel-font-lock--defface fuel-font-lock-debug-uses-header
   'bold fuel-debug "headers in Uses buffers")
 
@@ -53,26 +47,6 @@
             (forward-line))
           (reverse lines))))))
 
-(defun fuel-debug--highlight-names (names ref face)
-  (dolist (n names)
-    (when (not (member n ref))
-      (put-text-property 0 (length n) 'font-lock-face face n))))
-
-(defun fuel-debug--uses-new-uses (file uses)
-  (pop-to-buffer (find-file-noselect file))
-  (goto-char (point-min))
-  (if (re-search-forward "^USING: " nil t)
-      (let ((begin (point))
-            (end (or (and (re-search-forward "\\_<;\\_>") (point)) (point))))
-        (kill-region begin end))
-    (re-search-forward "^IN: " nil t)
-    (beginning-of-line)
-    (open-line 2)
-    (insert "USING: "))
-  (let ((start (point)))
-    (insert (mapconcat 'substring-no-properties uses " ") " ;")
-    (fill-region start (point) nil)))
-
 (defun fuel-debug--uses-filter (restarts)
   (let ((result) (i 1) (rn 0))
     (dolist (r restarts (reverse result))
@@ -87,9 +61,6 @@
 (fuel-popup--define fuel-debug--uses-buffer
   "*fuel uses*" 'fuel-debug-uses-mode)
 
-(make-variable-buffer-local
- (defvar fuel-debug--uses nil))
-
 (make-variable-buffer-local
  (defvar fuel-debug--uses-file nil))
 
@@ -122,27 +93,15 @@
     (fuel-popup--display (fuel-debug--uses-buffer))))
 
 (defun fuel-debug--uses-cont (retort)
-  (let ((uses (fuel-eval--retort-result retort))
+  (let ((uses (fuel-debug--uses retort))
         (err (fuel-eval--retort-error retort)))
     (if uses (fuel-debug--uses-display uses)
       (fuel-debug--uses-display-err retort))))
 
-(defun fuel-debug--insert-vlist (title vlist)
-  (goto-char (point-max))
-  (insert title "\n\n  ")
-  (let ((i 0) (step 5))
-    (dolist (v vlist)
-      (setq i (1+ i))
-      (insert v)
-      (insert (if (zerop (mod i step)) "\n  " " ")))
-    (unless (zerop (mod i step)) (newline))
-    (newline)))
-
 (defun fuel-debug--uses-display (uses)
   (let* ((inhibit-read-only t)
          (old (with-current-buffer (find-file-noselect fuel-debug--uses-file)
-                (fuel-syntax--usings)))
-         (old (sort old 'string<))
+                (sort (fuel-syntax--find-usings t) 'string<)))
          (new (sort uses 'string<)))
     (erase-buffer)
     (fuel-debug--uses-insert-title)
@@ -177,14 +136,15 @@
 
 (defun fuel-debug--uses-update-usings ()
   (interactive)
-  (let ((inhibit-read-only t))
-    (when (and fuel-debug--uses-file fuel-debug--uses)
-      (fuel-debug--uses-new-uses fuel-debug--uses-file fuel-debug--uses)
-      (message "USING: updated!")
-      (with-current-buffer (fuel-debug--uses-buffer)
-        (insert "\nDone!")
-        (fuel-debug--uses-clean)
-        (bury-buffer)))))
+  (let ((inhibit-read-only t)
+        (file fuel-debug--uses-file)
+        (uses fuel-debug--uses))
+    (when (and uses file)
+      (insert "\nDone!")
+      (fuel-debug--uses-clean)
+      (fuel-popup--quit)
+      (fuel-debug--replace-usings file uses)
+      (message "USING: updated!"))))
 
 (defun fuel-debug--uses-restart (n)
   (when (and (> n 0) (<= n (length fuel-debug--uses-restarts)))
@@ -210,11 +170,11 @@
 
 (defconst fuel-debug--uses-header-regex
   (format "^%s.*$" (regexp-opt '("Infering USING: stanza for "
-                              "Current USING: is already fine!"
-                              "Current vocabulary list:"
-                              "Correct vocabulary list:"
-                              "Sorry, couldn't infer the vocabulary list."
-                              "Done!"))))
+                                 "Current USING: is already fine!"
+                                 "Current vocabulary list:"
+                                 "Correct vocabulary list:"
+                                 "Sorry, couldn't infer the vocabulary list."
+                                 "Done!"))))
 
 (defconst fuel-debug--uses-prompt-regex
   (format "^%s" (regexp-opt '("Asking Factor. Please, wait ..."
diff --git a/misc/fuel/fuel-debug.el b/misc/fuel/fuel-debug.el
index f376bde1c9..4d84ad5141 100644
--- a/misc/fuel/fuel-debug.el
+++ b/misc/fuel/fuel-debug.el
@@ -31,6 +31,12 @@
   :group 'fuel-debug
   :type 'hook)
 
+(defcustom fuel-debug-confirm-restarts-p t
+  "Whether to ask for confimation before executing a restart in
+the debugger."
+  :group 'fuel-debug
+  :type 'boolean)
+
 (defcustom fuel-debug-show-short-help t
   "Whether to show short help on available keys in debugger."
   :group 'fuel-debug
@@ -43,7 +49,9 @@
   (column variable-name "column numbers in errors/warnings")
   (info comment "information headers")
   (restart-number warning "restart numbers")
-  (restart-name function-name "restart names")))
+  (restart-name function-name "restart names")
+  (missing-vocab warning"missing vocabulary names")
+  (unneeded-vocab warning "unneeded vocabulary names")))
 
 
 ;;; Font lock and other pattern matching:
@@ -92,6 +100,9 @@
 (make-variable-buffer-local
  (defvar fuel-debug--file nil))
 
+(make-variable-buffer-local
+ (defvar fuel-debug--uses nil))
+
 (defun fuel-debug--prepare-compilation (file msg)
   (let ((inhibit-read-only t))
     (with-current-buffer (fuel-debug--buffer)
@@ -114,6 +125,7 @@
         (fuel-debug--display-restarts err)
         (delete-blank-lines)
         (newline))
+      (fuel-debug--display-uses ret)
       (let ((hstr (fuel-debug--help-string err fuel-debug--file)))
         (if fuel-debug-show-short-help
             (insert "-----------\n" hstr "\n")
@@ -124,6 +136,46 @@
       (when (and err (not no-pop)) (fuel-popup--display))
       (not err))))
 
+(defun fuel-debug--uses (ret)
+  (let ((uses (fuel-eval--retort-result ret)))
+    (and (eq :uses (car uses))
+         (cdr uses))))
+
+(defun fuel-debug--insert-vlist (title vlist)
+  (goto-char (point-max))
+  (insert title "\n\n  ")
+  (let ((i 0) (step 5))
+    (dolist (v vlist)
+      (setq i (1+ i))
+      (insert v)
+      (insert (if (zerop (mod i step)) "\n  " " ")))
+    (unless (zerop (mod i step)) (newline))
+    (newline)))
+
+(defun fuel-debug--highlight-names (names ref face)
+  (dolist (n names)
+    (when (not (member n ref))
+      (put-text-property 0 (length n) 'font-lock-face face n))))
+
+(defun fuel-debug--insert-uses (uses)
+  (let* ((file (or file fuel-debug--file))
+         (old (with-current-buffer (find-file-noselect file)
+                (sort (fuel-syntax--find-usings t) 'string<)))
+         (new (sort uses 'string<)))
+    (when (not (equalp old new))
+      (fuel-debug--highlight-names old new 'fuel-font-lock-debug-unneeded-vocab)
+      (newline)
+      (fuel-debug--insert-vlist "Correct vocabulary list:" new)
+      new)))
+
+(defun fuel-debug--display-uses (ret)
+  (when (setq fuel-debug--uses (fuel-debug--uses ret))
+    (newline)
+    (fuel-debug--highlight-names fuel-debug--uses
+                                 nil 'fuel-font-lock-debug-missing-vocab)
+    (fuel-debug--insert-vlist "Missing vocabularies:" fuel-debug--uses)
+    (newline)))
+
 (defun fuel-debug--display-output (ret)
   (let* ((last (fuel-eval--retort-output fuel-debug--last-ret))
          (current (fuel-eval--retort-output ret))
@@ -149,7 +201,7 @@
       (newline))))
 
 (defun fuel-debug--help-string (err &optional file)
-  (format "Press %s%s%sq bury buffer"
+  (format "Press %s%s%s%sq bury buffer"
           (if (or file (fuel-eval--error-file err)) "g go to file, " "")
           (let ((rsn (length (fuel-eval--error-restarts err))))
             (cond ((zerop rsn) "")
@@ -160,7 +212,8 @@
               (save-excursion
                 (goto-char (point-min))
                 (when (search-forward (car ci) nil t)
-                  (setq str (format "%c %s, %s" (cdr ci) (car ci) str))))))))
+                  (setq str (format "%c %s, %s" (cdr ci) (car ci) str))))))
+          (if (and (not err) fuel-debug--uses) "u to update USING:, " "")))
 
 (defun fuel-debug--buffer-file ()
   (with-current-buffer (fuel-debug--buffer)
@@ -229,6 +282,31 @@
              (fuel-eval--send/wait `(:fuel ((:factor ,info)))) "")
       (error "Sorry, no %s info available" info))))
 
+(defun fuel-debug--replace-usings (file uses)
+  (pop-to-buffer (find-file-noselect file))
+  (goto-char (point-min))
+  (if (re-search-forward "^USING: " nil t)
+      (let ((begin (point))
+            (end (or (and (re-search-forward "\\_<;\\_>") (point)) (point))))
+        (kill-region begin end))
+    (re-search-forward "^IN: " nil t)
+    (beginning-of-line)
+    (open-line 2)
+    (insert "USING: "))
+  (let ((start (point)))
+    (insert (mapconcat 'substring-no-properties uses " ") " ;")
+    (fill-region start (point) nil)))
+
+(defun fuel-debug-update-usings ()
+  (interactive)
+  (when (and fuel-debug--file fuel-debug--uses)
+    (let* ((file fuel-debug--file)
+           (old (with-current-buffer (find-file-noselect file)
+                  (fuel-syntax--find-usings t)))
+           (uses (sort (append fuel-debug--uses old) 'string<)))
+      (fuel-popup--quit)
+      (fuel-debug--replace-usings file uses))))
+
 
 ;;; Fuel Debug mode:
 
@@ -239,9 +317,11 @@
     (define-key map "\C-c\C-c" 'fuel-debug-goto-error)
     (define-key map "n" 'next-line)
     (define-key map "p" 'previous-line)
+    (define-key map "u" 'fuel-debug-update-usings)
     (dotimes (n 9)
       (define-key map (vector (+ ?1 n))
-        `(lambda () (interactive) (fuel-debug-exec-restart ,(1+ n) t))))
+        `(lambda () (interactive)
+           (fuel-debug-exec-restart ,(1+ n) fuel-debug-confirm-restarts-p))))
     (dolist (ci fuel-debug--compiler-info-alist)
       (define-key map (vector (cdr ci))
         `(lambda () (interactive) (fuel-debug-show--compiler-info ,(car ci)))))
diff --git a/misc/fuel/fuel-font-lock.el b/misc/fuel/fuel-font-lock.el
index 1c37de7b18..d4ce88cf20 100644
--- a/misc/fuel/fuel-font-lock.el
+++ b/misc/fuel/fuel-font-lock.el
@@ -1,6 +1,6 @@
 ;;; fuel-font-lock.el -- font lock for factor code
 
-;; Copyright (C) 2008 Jose Antonio Ortega Ruiz
+;; Copyright (C) 2008, 2009 Jose Antonio Ortega Ruiz
 ;; See http://factorcode.org/license.txt for BSD license.
 
 ;; Author: Jose Antonio Ortega Ruiz <jao@gnu.org>
@@ -99,5 +99,24 @@
                          fuel-syntax--syntactic-keywords))))))
 
 
+
+;;; Fontify strings as Factor code:
+
+(defvar fuel-font-lock--font-lock-buffer
+  (let ((buffer (get-buffer-create " *fuel font lock*")))
+    (set-buffer buffer)
+    (set-syntax-table fuel-syntax--syntax-table)
+    (fuel-font-lock--font-lock-setup)
+    buffer))
+
+(defun fuel-font-lock--factor-str (str)
+  (save-current-buffer
+    (set-buffer fuel-font-lock--font-lock-buffer)
+    (erase-buffer)
+    (insert str)
+    (let ((font-lock-verbose nil)) (font-lock-fontify-buffer))
+    (buffer-string)))
+
+
 (provide 'fuel-font-lock)
 ;;; fuel-font-lock.el ends here
diff --git a/misc/fuel/fuel-help.el b/misc/fuel/fuel-help.el
index 9216a9fd02..12091ea399 100644
--- a/misc/fuel/fuel-help.el
+++ b/misc/fuel/fuel-help.el
@@ -1,6 +1,6 @@
 ;;; fuel-help.el -- accessing Factor's help system
 
-;; Copyright (C) 2008 Jose Antonio Ortega Ruiz
+;; Copyright (C) 2008, 2009 Jose Antonio Ortega Ruiz
 ;; See http://factorcode.org/license.txt for BSD license.
 
 ;; Author: Jose Antonio Ortega Ruiz <jao@gnu.org>
@@ -15,12 +15,16 @@
 ;;; Code:
 
 (require 'fuel-eval)
+(require 'fuel-markup)
 (require 'fuel-autodoc)
+(require 'fuel-xref)
 (require 'fuel-completion)
 (require 'fuel-font-lock)
 (require 'fuel-popup)
 (require 'fuel-base)
 
+(require 'button)
+
 
 ;;; Customization:
 
@@ -33,37 +37,35 @@
   :type 'boolean
   :group 'fuel-help)
 
-(defcustom fuel-help-use-minibuffer t
-  "When enabled, use the minibuffer for short help messages."
-  :type 'boolean
-  :group 'fuel-help)
-
-(defcustom fuel-help-mode-hook nil
-  "Hook run by `factor-help-mode'."
-  :type 'hook
-  :group 'fuel-help)
-
 (defcustom fuel-help-history-cache-size 50
   "Maximum number of pages to keep in the help browser cache."
   :type 'integer
   :group 'fuel-help)
 
-(fuel-font-lock--defface fuel-font-lock-help-headlines
-  'bold fuel-hep "headlines in help buffers")
+(defcustom fuel-help-bookmarks nil
+  "Bookmars. Maintain this list using the help browser."
+  :type 'list
+  :group 'fuel-help)
 
 
 ;;; Help browser history:
 
-(defvar fuel-help--history
+(defun fuel-help--make-history ()
   (list nil                                        ; current
         (make-ring fuel-help-history-cache-size)   ; previous
         (make-ring fuel-help-history-cache-size))) ; next
 
-(defun fuel-help--history-push (term)
-  (when (and (car fuel-help--history)
-             (not (string= (caar fuel-help--history) (car term))))
-    (ring-insert (nth 1 fuel-help--history) (car fuel-help--history)))
-  (setcar fuel-help--history term))
+(defsubst fuel-help--history-current ()
+  (car fuel-help--history))
+
+(defun fuel-help--history-push (link)
+  (unless (equal link (car fuel-help--history))
+    (let ((next (fuel-help--history-next)))
+      (unless (equal link next)
+        (when next (fuel-help--history-previous))
+        (ring-insert (nth 1 fuel-help--history) (car fuel-help--history))
+        (setcar fuel-help--history link))))
+  link)
 
 (defun fuel-help--history-next ()
   (when (not (ring-empty-p (nth 2 fuel-help--history)))
@@ -77,6 +79,25 @@
       (ring-insert (nth 2 fuel-help--history) (car fuel-help--history)))
     (setcar fuel-help--history (ring-remove (nth 1 fuel-help--history) 0))))
 
+(defvar fuel-help--history (fuel-help--make-history))
+
+
+;;; Page cache:
+
+(defun fuel-help--history-current-content ()
+  (fuel-help--cache-get (car fuel-help--history)))
+
+(defvar fuel-help--cache (make-hash-table :weakness 'key :test 'equal))
+
+(defsubst fuel-help--cache-get (name)
+  (gethash name fuel-help--cache))
+
+(defsubst fuel-help--cache-insert (name str)
+  (puthash name str fuel-help--cache))
+
+(defsubst fuel-help--cache-clear ()
+  (clrhash fuel-help--cache))
+
 
 ;;; Fuel help buffer and internals:
 
@@ -86,121 +107,158 @@
 
 (defvar fuel-help--prompt-history nil)
 
-(defun fuel-help--show-help (&optional see word)
-  (let* ((def (or word (fuel-syntax-symbol-at-point)))
+(make-local-variable
+ (defvar fuel-help--buffer-link nil))
+
+(defun fuel-help--read-word (see)
+  (let* ((def (fuel-syntax-symbol-at-point))
          (prompt (format "See%s help on%s: " (if see " short" "")
                          (if def (format " (%s)" def) "")))
          (ask (or (not (memq major-mode '(factor-mode fuel-help-mode)))
                   (not def)
-                  fuel-help-always-ask))
-         (def (if ask (fuel-completion--read-word prompt
-                                                  def
-                                                  'fuel-help--prompt-history
-                                                  t)
-                def))
-         (cmd `(:fuel* ((:quote ,def) ,(if see 'see 'help)) t)))
-    (message "Looking up '%s' ..." def)
-    (fuel-eval--send cmd `(lambda (r) (fuel-help--show-help-cont ,def r)))))
+                  fuel-help-always-ask)))
+    (if ask (fuel-completion--read-word prompt
+                                        def
+                                        'fuel-help--prompt-history
+                                        t)
+      def)))
 
-(defun fuel-help--show-help-cont (def ret)
-  (let ((out (fuel-eval--retort-output ret)))
-    (if (or (fuel-eval--retort-error ret) (empty-string-p out))
-        (message "No help for '%s'" def)
-      (fuel-help--insert-contents def out))))
+(defun fuel-help--word-help (&optional see word)
+  (let ((def (or word (fuel-help--read-word see))))
+    (when def
+      (let ((cmd `(:fuel* (,def ,(if see 'fuel-word-see 'fuel-word-help))
+                          "fuel" t)))
+        (message "Looking up '%s' ..." def)
+        (let* ((ret (fuel-eval--send/wait cmd 2000))
+               (res (fuel-eval--retort-result ret)))
+          (if (not res)
+              (message "No help for '%s'" def)
+            (fuel-help--insert-contents (list def def 'word) res)))))))
 
-(defun fuel-help--insert-contents (def str &optional nopush)
+(defun fuel-help--get-article (name label)
+  (message "Retrieving article ...")
+  (let* ((cmd `(:fuel* ((,name fuel-get-article)) "fuel" t))
+         (ret (fuel-eval--send/wait cmd 2000))
+         (res (fuel-eval--retort-result ret)))
+    (if (not res)
+        (message "Article '%s' not found" label)
+      (fuel-help--insert-contents (list name label 'article) res)
+      (message ""))))
+
+(defun fuel-help--get-vocab (name)
+  (message "Retrieving vocabulary help ...")
+  (let* ((cmd `(:fuel* ((,name fuel-vocab-help)) "fuel" (,name)))
+         (ret (fuel-eval--send/wait cmd 2000))
+         (res (fuel-eval--retort-result ret)))
+    (if (not res)
+        (message "No help available for vocabulary '%s'" name)
+      (fuel-help--insert-contents (list name name 'vocab) res)
+      (message ""))))
+
+(defun fuel-help--follow-link (link label type &optional no-cache)
+  (let* ((llink (list link label type))
+         (cached (and (not no-cache) (fuel-help--cache-get llink))))
+    (if (not cached)
+        (let ((fuel-help-always-ask nil))
+          (cond ((eq type 'word) (fuel-help--word-help nil link))
+                ((eq type 'article) (fuel-help--get-article link label))
+                ((eq type 'vocab) (fuel-help--get-vocab link))
+                ((eq type 'bookmarks) (fuel-help-display-bookmarks))
+                (t (error "Links of type %s not yet implemented" type))))
+      (fuel-help--insert-contents llink cached))))
+
+(defun fuel-help--insert-contents (key content)
   (let ((hb (fuel-help--buffer))
         (inhibit-read-only t)
         (font-lock-verbose nil))
     (set-buffer hb)
     (erase-buffer)
-    (insert str)
-    (unless nopush
-      (goto-char (point-min))
-      (when (re-search-forward (format "^%s" def) nil t)
-        (beginning-of-line)
-        (kill-region (point-min) (point))
-        (fuel-help--history-push (cons def (buffer-string)))))
+    (if (stringp content)
+        (insert content)
+      (fuel-markup--print content)
+      (fuel-markup--insert-newline)
+      (fuel-help--cache-insert key (buffer-string)))
+    (fuel-help--history-push key)
+    (setq fuel-help--buffer-link key)
     (set-buffer-modified-p nil)
     (fuel-popup--display)
     (goto-char (point-min))
-    (message "%s" def)))
+    (message "")))
 
 
-;;; Help mode font lock:
+;;; Bookmarks:
 
-(defconst fuel-help--headlines
-  (regexp-opt '("Class description"
-                "Definition"
-                "Errors"
-                "Examples"
-                "Generic word contract"
-                "Inputs and outputs"
-                "Methods"
-                "Notes"
-                "Parent topics:"
-                "See also"
-                "Syntax"
-                "Variable description"
-                "Variable value"
-                "Vocabulary"
-                "Warning"
-                "Word description")
-              t))
+(defun fuel-help-bookmark-page ()
+  "Add current help page to bookmarks."
+  (interactive)
+  (let ((link fuel-help--buffer-link))
+    (unless link (error "No link associated to this page"))
+    (add-to-list 'fuel-help-bookmarks link)
+    (customize-save-variable 'fuel-help-bookmarks fuel-help-bookmarks)
+    (message "Bookmark '%s' saved" (cadr link))))
 
-(defconst fuel-help--headlines-regexp (format "^%s" fuel-help--headlines))
-
-(defconst fuel-help--font-lock-keywords
-  `(,@fuel-font-lock--font-lock-keywords
-    (,fuel-help--headlines-regexp . 'fuel-font-lock-help-headlines)))
+(defun fuel-help-delete-bookmark ()
+  "Delete link at point from bookmarks."
+  (interactive)
+  (let ((link (fuel-markup--link-at-point)))
+    (unless link (error "No link at point"))
+    (unless (member link fuel-help-bookmarks)
+      (error "'%s' is not bookmarked" (cadr link)))
+    (customize-save-variable 'fuel-help-bookmarks
+                             (remove link fuel-help-bookmarks))
+    (message "Bookmark '%s' delete" (cadr link))
+    (fuel-help-display-bookmarks)))
 
+(defun fuel-help-display-bookmarks ()
+  "Display bookmarked pages."
+  (interactive)
+  (let ((links (mapcar (lambda (l) (cons '$subsection l)) fuel-help-bookmarks)))
+    (unless links (error "No links to display"))
+    (fuel-help--insert-contents '("bookmarks" "Bookmars" bookmarks)
+                                `(article "Bookmarks" ,links))))
 
 
 ;;; Interactive help commands:
 
-(defun fuel-help-short (&optional arg)
-  "See a help summary of symbol at point.
-By default, the information is shown in the minibuffer. When
-called with a prefix argument, the information is displayed in a
-separate help buffer."
-  (interactive "P")
-  (if (if fuel-help-use-minibuffer (not arg) arg)
-      (fuel-help--word-synopsis)
-    (fuel-help--show-help t)))
+(defun fuel-help-short ()
+  "See help summary of symbol at point."
+  (interactive)
+  (fuel-help--word-help t))
 
 (defun fuel-help ()
   "Show extended help about the symbol at point, using a help
 buffer."
   (interactive)
-  (fuel-help--show-help))
+  (fuel-help--word-help))
 
 (defun fuel-help-next ()
   "Go to next page in help browser."
   (interactive)
-  (let ((item (fuel-help--history-next))
-        (fuel-help-always-ask nil))
-    (unless item
-      (error "No next page"))
-    (fuel-help--insert-contents (car item) (cdr item) t)))
+  (let ((item (fuel-help--history-next)))
+    (unless item (error "No next page"))
+    (apply 'fuel-help--follow-link item)))
 
 (defun fuel-help-previous ()
-  "Go to next page in help browser."
+  "Go to previous page in help browser."
   (interactive)
-  (let ((item (fuel-help--history-previous))
-        (fuel-help-always-ask nil))
-    (unless item
-      (error "No previous page"))
-    (fuel-help--insert-contents (car item) (cdr item) t)))
+  (let ((item (fuel-help--history-previous)))
+    (unless item (error "No previous page"))
+    (apply 'fuel-help--follow-link item)))
 
-(defun fuel-help-next-headline (&optional count)
-  (interactive "P")
-  (end-of-line)
-  (when (re-search-forward fuel-help--headlines-regexp nil t (or count 1))
-    (beginning-of-line)))
+(defun fuel-help-refresh ()
+  "Refresh the contents of current page."
+  (interactive)
+  (when fuel-help--buffer-link
+    (apply 'fuel-help--follow-link (append fuel-help--buffer-link '(t)))))
 
-(defun fuel-help-previous-headline (&optional count)
-  (interactive "P")
-  (re-search-backward fuel-help--headlines-regexp nil t count))
+(defun fuel-help-clean-history ()
+  "Clean up the help browser cache of visited pages."
+  (interactive)
+  (when (y-or-n-p "Clean browsing history? ")
+    (fuel-help--cache-clear)
+    (setq fuel-help--history (fuel-help--make-history))
+    (fuel-help-refresh))
+  (message ""))
 
 
 ;;;; Help mode map:
@@ -208,15 +266,16 @@ buffer."
 (defvar fuel-help-mode-map
   (let ((map (make-sparse-keymap)))
     (suppress-keymap map)
-    (define-key map "\C-m" 'fuel-help)
-    (define-key map "b" 'fuel-help-previous)
-    (define-key map "f" 'fuel-help-next)
-    (define-key map "l" 'fuel-help-previous)
-    (define-key map "p" 'fuel-help-previous)
+    (set-keymap-parent map button-buffer-map)
+    (define-key map "a" 'fuel-apropos)
+    (define-key map "ba" 'fuel-help-bookmark-page)
+    (define-key map "bb" 'fuel-help-display-bookmarks)
+    (define-key map "bd" 'fuel-help-delete-bookmark)
+    (define-key map "c" 'fuel-help-clean-history)
+    (define-key map "h" 'fuel-help)
     (define-key map "n" 'fuel-help-next)
-    (define-key map (kbd "TAB") 'fuel-help-next-headline)
-    (define-key map (kbd "S-TAB") 'fuel-help-previous-headline)
-    (define-key map [(backtab)] 'fuel-help-previous-headline)
+    (define-key map "p" 'fuel-help-previous)
+    (define-key map "r" 'fuel-help-refresh)
     (define-key map (kbd "SPC")  'scroll-up)
     (define-key map (kbd "S-SPC") 'scroll-down)
     (define-key map "\M-." 'fuel-edit-word-at-point)
@@ -234,16 +293,10 @@ buffer."
   (kill-all-local-variables)
   (buffer-disable-undo)
   (use-local-map fuel-help-mode-map)
+  (set-syntax-table fuel-syntax--syntax-table)
   (setq mode-name "FUEL Help")
   (setq major-mode 'fuel-help-mode)
-
-  (fuel-font-lock--font-lock-setup fuel-help--font-lock-keywords t)
-
-  (setq fuel-autodoc-mode-string "")
-  (fuel-autodoc-mode)
-
-  (run-mode-hooks 'fuel-help-mode-hook)
-
+  (setq fuel-markup--follow-link-function 'fuel-help--follow-link)
   (setq buffer-read-only t))
 
 
diff --git a/misc/fuel/fuel-listener.el b/misc/fuel/fuel-listener.el
index eb159eb56e..ecb47f68a2 100644
--- a/misc/fuel/fuel-listener.el
+++ b/misc/fuel/fuel-listener.el
@@ -1,6 +1,6 @@
 ;;; fuel-listener.el --- starting the fuel listener
 
-;; Copyright (C) 2008  Jose Antonio Ortega Ruiz
+;; Copyright (C) 2008, 2009  Jose Antonio Ortega Ruiz
 ;; See http://factorcode.org/license.txt for BSD license.
 
 ;; Author: Jose Antonio Ortega Ruiz <jao@gnu.org>
@@ -15,6 +15,7 @@
 
 (require 'fuel-stack)
 (require 'fuel-completion)
+(require 'fuel-xref)
 (require 'fuel-eval)
 (require 'fuel-connection)
 (require 'fuel-syntax)
@@ -169,6 +170,7 @@ buffer."
 (define-key fuel-listener-mode-map "\C-ca" 'fuel-autodoc-mode)
 (define-key fuel-listener-mode-map "\C-ch" 'fuel-help)
 (define-key fuel-listener-mode-map "\C-cs" 'fuel-stack-mode)
+(define-key fuel-listener-mode-map "\C-cp" 'fuel-apropos)
 (define-key fuel-listener-mode-map "\M-." 'fuel-edit-word-at-point)
 (define-key fuel-listener-mode-map "\C-cv" 'fuel-edit-vocabulary)
 (define-key fuel-listener-mode-map "\C-c\C-v" 'fuel-edit-vocabulary)
diff --git a/misc/fuel/fuel-markup.el b/misc/fuel/fuel-markup.el
new file mode 100644
index 0000000000..a2c94d4f4a
--- /dev/null
+++ b/misc/fuel/fuel-markup.el
@@ -0,0 +1,479 @@
+;;; fuel-markup.el -- printing factor help markup
+
+;; Copyright (C) 2009 Jose Antonio Ortega Ruiz
+;; See http://factorcode.org/license.txt for BSD license.
+
+;; Author: Jose Antonio Ortega Ruiz <jao@gnu.org>
+;; Keywords: languages, fuel, factor
+;; Start date: Thu Jan 01, 2009 21:43
+
+;;; Comentary:
+
+;; Utilities for printing Factor's help markup.
+
+;;; Code:
+
+(require 'fuel-eval)
+(require 'fuel-font-lock)
+(require 'fuel-base)
+
+(require 'button)
+(require 'table)
+
+
+;;; Customization:
+
+(fuel-font-lock--defface fuel-font-lock-markup-title
+  'bold fuel-help "article titles in help buffers")
+
+(fuel-font-lock--defface fuel-font-lock-markup-heading
+  'bold fuel-help "headlines in help buffers")
+
+(fuel-font-lock--defface fuel-font-lock-markup-link
+  'link fuel-help "links to topics in help buffers")
+
+(fuel-font-lock--defface fuel-font-lock-markup-emphasis
+  'italic fuel-help "emphasized words in help buffers")
+
+(fuel-font-lock--defface fuel-font-lock-markup-strong
+  'link fuel-help "bold words in help buffers")
+
+
+;;; Links:
+
+(make-variable-buffer-local
+ (defvar fuel-markup--follow-link-function 'fuel-markup--echo-link))
+
+(define-button-type 'fuel-markup--button
+  'action 'fuel-markup--follow-link
+  'face 'fuel-font-lock-markup-link
+  'follow-link t)
+
+(defun fuel-markup--follow-link (button)
+  (when fuel-markup--follow-link-function
+    (funcall fuel-markup--follow-link-function
+             (button-get button 'markup-link)
+             (button-get button 'markup-label)
+             (button-get button 'markup-link-type))))
+
+(defun fuel-markup--echo-link (link label type)
+  (message "Link %s pointing to %s named %s" label type link))
+
+(defun fuel-markup--insert-button (label link type)
+  (let ((label (format "%s" label))
+        (link (format "%s" link)))
+    (insert-text-button label
+                        :type 'fuel-markup--button
+                        'markup-link link
+                        'markup-label label
+                        'markup-link-type type
+                        'help-echo (format "%s (%s)" label type))))
+
+(defun fuel-markup--article-title (name)
+  (fuel-eval--retort-result
+   (fuel-eval--send/wait `(:fuel* ((,name fuel-article-title :get)) "fuel"))))
+
+(defun fuel-markup--link-at-point ()
+  (let ((button (condition-case nil (forward-button 0) (error nil))))
+    (when button
+      (list (button-get button 'markup-link)
+            (button-get button 'markup-label)
+            (button-get button 'markup-link-type)))))
+
+
+;;; Markup printers:
+
+(defconst fuel-markup--printers
+  '(($class-description . fuel-markup--class-description)
+    ($code . fuel-markup--code)
+    ($command . fuel-markup--command)
+    ($contract . fuel-markup--contract)
+    ($curious . fuel-markup--curious)
+    ($definition . fuel-markup--definition)
+    ($description . fuel-markup--description)
+    ($doc-path . fuel-markup--doc-path)
+    ($emphasis . fuel-markup--emphasis)
+    ($error-description . fuel-markup--error-description)
+    ($errors . fuel-markup--errors)
+    ($example . fuel-markup--example)
+    ($examples . fuel-markup--examples)
+    ($heading . fuel-markup--heading)
+    ($index . fuel-markup--index)
+    ($instance . fuel-markup--instance)
+    ($io-error . fuel-markup--io-error)
+    ($link . fuel-markup--link)
+    ($links . fuel-markup--links)
+    ($list . fuel-markup--list)
+    ($low-level-note . fuel-markup--low-level-note)
+    ($markup-example . fuel-markup--markup-example)
+    ($maybe . fuel-markup--maybe)
+    ($methods . fuel-markup--methods)
+    ($nl . fuel-markup--newline)
+    ($notes . fuel-markup--notes)
+    ($parsing-note . fuel-markup--parsing-note)
+    ($predicate . fuel-markup--predicate)
+    ($prettyprinting-note . fuel-markup--prettyprinting-note)
+    ($quotation . fuel-markup--quotation)
+    ($references . fuel-markup--references)
+    ($related . fuel-markup--related)
+    ($see . fuel-markup--see)
+    ($see-also . fuel-markup--see-also)
+    ($shuffle . fuel-markup--shuffle)
+    ($side-effects . fuel-markup--side-effects)
+    ($slot . fuel-markup--snippet)
+    ($snippet . fuel-markup--snippet)
+    ($strong . fuel-markup--strong)
+    ($subheading . fuel-markup--subheading)
+    ($subsection . fuel-markup--subsection)
+    ($synopsis . fuel-markup--synopsis)
+    ($syntax . fuel-markup--syntax)
+    ($table . fuel-markup--table)
+    ($unchecked-example . fuel-markup--example)
+    ($value . fuel-markup--value)
+    ($values . fuel-markup--values)
+    ($values-x/y . fuel-markup--values-x/y)
+    ($var-description . fuel-markup--var-description)
+    ($vocab-link . fuel-markup--vocab-link)
+    ($vocab-links . fuel-markup--vocab-links)
+    ($vocab-subsection . fuel-markup--vocab-subsection)
+    ($vocabulary . fuel-markup--vocabulary)
+    ($warning . fuel-markup--warning)
+    (article . fuel-markup--article)))
+
+(make-variable-buffer-local
+ (defvar fuel-markup--maybe-nl nil))
+
+(defun fuel-markup--print (e)
+  (cond ((null e))
+        ((stringp e) (fuel-markup--insert-string e))
+        ((and (listp e) (symbolp (car e))
+              (assoc (car e) fuel-markup--printers))
+         (funcall (cdr (assoc (car e) fuel-markup--printers)) e))
+        ((and (symbolp e)
+              (assoc e fuel-markup--printers))
+         (funcall (cdr (assoc e fuel-markup--printers)) e))
+        ((listp e) (mapc 'fuel-markup--print e))
+        ((symbolp e) (fuel-markup--print (list '$link e)))
+        (t (insert (format "\n%S\n" e)))))
+
+(defun fuel-markup--print-str (e)
+  (with-temp-buffer
+    (fuel-markup--print e)
+    (buffer-string)))
+
+(defun fuel-markup--maybe-nl ()
+  (setq fuel-markup--maybe-nl (point)))
+
+(defun fuel-markup--insert-newline (&optional justification)
+  (fill-region (save-excursion (beginning-of-line) (point))
+               (point)
+               (or justification 'left))
+  (newline))
+
+(defsubst fuel-markup--insert-nl-if-nb (&optional no-fill)
+  (unless (eq (save-excursion (beginning-of-line) (point)) (point))
+    (if no-fill (newline) (fuel-markup--insert-newline))))
+
+(defsubst fuel-markup--put-face (txt face)
+  (put-text-property 0 (length txt) 'font-lock-face face txt)
+  txt)
+
+(defun fuel-markup--insert-heading (txt &optional no-nl)
+  (fuel-markup--insert-nl-if-nb)
+  (unless (bobp) (newline))
+  (fuel-markup--put-face txt 'fuel-font-lock-markup-heading)
+  (fuel-markup--insert-string txt)
+  (unless no-nl (newline)))
+
+(defun fuel-markup--insert-string (str)
+  (when fuel-markup--maybe-nl
+    (newline 2)
+    (setq fuel-markup--maybe-nl nil))
+  (insert str))
+
+(defun fuel-markup--article (e)
+  (setq fuel-markup--maybe-nl nil)
+  (insert (fuel-markup--put-face (cadr e) 'fuel-font-lock-markup-title))
+  (newline 2)
+  (fuel-markup--print (car (cddr e))))
+
+(defun fuel-markup--heading (e)
+  (fuel-markup--insert-heading (cadr e)))
+
+(defun fuel-markup--subheading (e)
+  (fuel-markup--insert-heading (cadr e)))
+
+(defun fuel-markup--subsection (e)
+  (fuel-markup--insert-nl-if-nb)
+  (insert "  - ")
+  (fuel-markup--link (cons '$link (cdr e)))
+  (fuel-markup--maybe-nl))
+
+(defun fuel-markup--vocab-subsection (e)
+  (fuel-markup--insert-nl-if-nb)
+  (insert "  - ")
+  (fuel-markup--vocab-link (cons '$vocab-link (cdr e)))
+  (fuel-markup--maybe-nl))
+
+(defun fuel-markup--newline (e)
+  (fuel-markup--insert-newline)
+  (newline))
+
+(defun fuel-markup--doc-path (e)
+  (fuel-markup--insert-heading "Related topics")
+  (insert "  ")
+  (dolist (art (cdr e))
+    (fuel-markup--insert-button (car art) (cadr art) 'article)
+    (insert ", "))
+  (delete-backward-char 2)
+  (fuel-markup--insert-newline 'left))
+
+(defun fuel-markup--emphasis (e)
+  (when (stringp (cadr e))
+    (fuel-markup--put-face (cadr e) 'fuel-font-lock-markup-emphasis)
+    (insert (cadr e))))
+
+(defun fuel-markup--strong (e)
+  (when (stringp (cadr e))
+    (fuel-markup--put-face (cadr e) 'fuel-font-lock-markup-strong)
+    (insert (cadr e))))
+
+(defun fuel-markup--snippet (e)
+  (let ((snip (format "%s" (cdr e))))
+    (insert (fuel-font-lock--factor-str snip))))
+
+(defun fuel-markup--code (e)
+  (fuel-markup--insert-nl-if-nb)
+  (newline)
+  (dolist (snip (cdr e))
+    (if (stringp snip)
+        (insert (fuel-font-lock--factor-str snip))
+      (fuel-markup--print snip))
+    (newline))
+  (newline))
+
+(defun fuel-markup--command (e)
+  (fuel-markup--snippet (list '$snippet (nth 3 e))))
+
+(defun fuel-markup--syntax (e)
+  (fuel-markup--insert-heading "Syntax")
+  (fuel-markup--print (cons '$code (cdr e)))
+  (newline))
+
+(defun fuel-markup--examples (e)
+  (fuel-markup--insert-heading "Examples")
+  (dolist (ex (cdr e))
+    (fuel-markup--print ex)
+    (newline)))
+
+(defun fuel-markup--example (e)
+  (fuel-markup--snippet (list '$snippet (cadr e))))
+
+(defun fuel-markup--markup-example (e)
+  (fuel-markup--snippet (cons '$snippet (cadr e))))
+
+(defun fuel-markup--link (e)
+  (let* ((link (nth 1 e))
+         (type (or (nth 3 e) (if (symbolp link) 'word 'article)))
+         (label (or (nth 2 e)
+                    (and (eq type 'article)
+                         (fuel-markup--article-title link))
+                    link)))
+    (fuel-markup--insert-button label link type)))
+
+(defun fuel-markup--links (e)
+  (dolist (link (cdr e))
+    (fuel-markup--link (list '$link link))
+    (insert ", "))
+  (delete-backward-char 2))
+
+(defun fuel-markup--index-quotation (q)
+  (cond ((null q) null)
+        ((listp q) (vconcat (mapcar 'fuel-markup--index-quotation q)))
+        (t q)))
+
+(defun fuel-markup--index (e)
+  (let* ((q (fuel-markup--index-quotation (cadr e)))
+         (cmd `(:fuel* ((,q fuel-index)) "fuel"
+                       ("builtins" "help" "help.topics" "classes"
+                        "classes.builtin" "classes.tuple"
+                        "classes.singleton" "classes.union"
+                        "classes.intersection" "classes.predicate")))
+         (subs (fuel-eval--retort-result (fuel-eval--send/wait cmd 200))))
+    (when subs
+      (fuel-markup--print subs))))
+
+(defun fuel-markup--vocab-link (e)
+  (fuel-markup--insert-button (cadr e) (cadr e) 'vocab))
+
+(defun fuel-markup--vocab-links (e)
+  (dolist (link (cdr e))
+    (insert " ")
+    (fuel-markup--vocab-link (list '$vocab-link link))
+    (insert " ")))
+
+(defun fuel-markup--vocabulary (e)
+  (fuel-markup--insert-heading "Vocabulary: " t)
+  (fuel-markup--vocab-link (cons '$vocab-link (cdr e)))
+  (newline))
+
+(defun fuel-markup--list (e)
+  (fuel-markup--insert-nl-if-nb)
+  (dolist (elt (cdr e))
+    (insert " - ")
+    (fuel-markup--print elt)
+    (fuel-markup--insert-newline)))
+
+(defun fuel-markup--table (e)
+  (fuel-markup--insert-newline)
+  (newline)
+  (let ((start (point))
+        (col-delim "<~end-of-col~>")
+        (col-no (length (cadr e))))
+    (dolist (row (cdr e))
+      (dolist (col row)
+        (fuel-markup--print col)
+        (insert col-delim)))
+    (table-capture start (point)
+                   col-delim nil nil
+                   (/ (- (window-width) 10) col-no) col-no))
+  (goto-char (point-max))
+  (table-recognize -1)
+  (newline))
+
+(defun fuel-markup--instance (e)
+  (insert " an instance of ")
+  (fuel-markup--print (cadr e)))
+
+(defun fuel-markup--maybe (e)
+  (fuel-markup--instance (cons '$instance (cdr e)))
+  (insert " or f "))
+
+(defun fuel-markup--values (e)
+  (fuel-markup--insert-heading "Inputs and outputs")
+  (dolist (val (cdr e))
+    (insert " " (car val) " - ")
+    (fuel-markup--print (cdr val))
+    (newline)))
+
+(defun fuel-markup--predicate (e)
+  (fuel-markup--values '($values ("object" object) ("?" "a boolean")))
+  (let ((word (make-symbol (substring (format "%s" (cadr e)) 0 -1))))
+  (fuel-markup--description
+   `($description "Tests if the object is an instance of the "
+                  ($link ,word) " class."))))
+
+(defun fuel-markup--side-effects (e)
+  (fuel-markup--insert-heading "Side effects")
+  (insert "Modifies ")
+  (fuel-markup--print (cdr e))
+  (fuel-markup--insert-newline))
+
+(defun fuel-markup--definition (e)
+  (fuel-markup--insert-heading "Definition")
+  (fuel-markup--code (cons '$code (cdr e))))
+
+(defun fuel-markup--methods (e)
+  (fuel-markup--insert-heading "Methods")
+  (fuel-markup--code (cons '$code (cdr e))))
+
+(defun fuel-markup--value (e)
+  (fuel-markup--insert-heading "Variable value")
+  (insert "Current value in global namespace: ")
+  (fuel-markup--snippet (cons '$snippet (cdr e)))
+  (newline))
+
+(defun fuel-markup--values-x/y (e)
+  (fuel-markup--values '($values ("x" "number") ("y" "number"))))
+
+(defun fuel-markup--curious (e)
+  (fuel-markup--insert-heading "For the curious...")
+  (fuel-markup--print (cdr e)))
+
+(defun fuel-markup--references (e)
+  (fuel-markup--insert-heading "References")
+  (dolist (ref (cdr e))
+    (if (listp ref)
+        (fuel-markup--print ref)
+      (fuel-markup--subsection (list '$subsection ref)))))
+
+(defun fuel-markup--see-also (e)
+  (fuel-markup--insert-heading "See also")
+  (fuel-markup--links (cons '$links (cdr e))))
+
+(defun fuel-markup--related (e)
+  (fuel-markup--insert-heading "See also")
+  (fuel-markup--links (cons '$links (cadr e))))
+
+(defun fuel-markup--shuffle (e)
+  (insert "\nShuffle word. Re-arranges the stack "
+          "according to the stack effect pattern.")
+  (fuel-markup--insert-newline))
+
+(defun fuel-markup--low-level-note (e)
+  (fuel-markup--print '($notes "Calling this word directly is not necessary "
+                               "in most cases. "
+                               "Higher-level words call it automatically.")))
+
+(defun fuel-markup--parsing-note (e)
+  (fuel-markup--insert-nl-if-nb)
+  (insert "This word should only be called from parsing words.")
+  (fuel-markup--insert-newline))
+
+(defun fuel-markup--io-error (e)
+  (fuel-markup--errors '($errors "Throws an error if the I/O operation fails.")))
+
+(defun fuel-markup--prettyprinting-note (e)
+  (fuel-markup--print '($notes ("This word should only be called within the "
+                                ($link with-pprint) " combinator."))))
+
+(defun fuel-markup--elem-with-heading (elem heading)
+  (fuel-markup--insert-heading heading)
+  (fuel-markup--print (cdr elem))
+  (fuel-markup--insert-newline))
+
+(defun fuel-markup--quotation (e)
+  (insert "a ")
+  (fuel-markup--link (list '$link 'quotation 'quotation 'word))
+  (insert " with stack effect ")
+  (fuel-markup--snippet (list '$snippet (nth 1 e))))
+
+(defun fuel-markup--warning (e)
+  (fuel-markup--elem-with-heading e "Warning"))
+
+(defun fuel-markup--description (e)
+  (fuel-markup--elem-with-heading e "Word description"))
+
+(defun fuel-markup--class-description (e)
+  (fuel-markup--elem-with-heading e "Class description"))
+
+(defun fuel-markup--error-description (e)
+  (fuel-markup--elem-with-heading e "Error description"))
+
+(defun fuel-markup--var-description (e)
+  (fuel-markup--elem-with-heading e "Variable description"))
+
+(defun fuel-markup--contract (e)
+  (fuel-markup--elem-with-heading e "Generic word contract"))
+
+(defun fuel-markup--errors (e)
+  (fuel-markup--elem-with-heading e "Errors"))
+
+(defun fuel-markup--notes (e)
+  (fuel-markup--elem-with-heading e "Notes"))
+
+(defun fuel-markup--see (e)
+  (let* ((word (nth 1 e))
+         (cmd (and word `(:fuel* (,(format "%s" word) fuel-word-see) "fuel" t)))
+         (res (and cmd
+                   (fuel-eval--retort-result (fuel-eval--send/wait cmd 100)))))
+    (if res
+        (fuel-markup--code (list '$code res))
+      (fuel-markup--snippet (list '$snippet word)))))
+
+(defun fuel-markup--synopsis (e)
+  (insert (format " %S " e)))
+
+
+(provide 'fuel-markup)
+;;; fuel-markup.el ends here
diff --git a/misc/fuel/fuel-mode.el b/misc/fuel/fuel-mode.el
index 1074f60f5f..df06584fab 100644
--- a/misc/fuel/fuel-mode.el
+++ b/misc/fuel/fuel-mode.el
@@ -1,6 +1,6 @@
 ;;; fuel-mode.el -- Minor mode enabling FUEL niceties
 
-;; Copyright (C) 2008 Jose Antonio Ortega Ruiz
+;; Copyright (C) 2008, 2009 Jose Antonio Ortega Ruiz
 ;; See http://factorcode.org/license.txt for BSD license.
 
 ;; Author: Jose Antonio Ortega Ruiz <jao@gnu.org>
@@ -224,6 +224,11 @@ With prefix argument, ask for word."
       (message "Looking up %s's callees ..." word)
       (fuel-xref--show-callees word))))
 
+(defun fuel-apropos (str)
+  "Show a list of words containing the given substring."
+  (interactive "MFind words containing: ")
+  (message "Looking up %s's references ..." str)
+  (fuel-xref--apropos str))
 
 ;;; Minor mode definition:
 
@@ -289,6 +294,7 @@ interacting with a factor listener is at your disposal.
 (fuel-mode--key ?d ?> 'fuel-show-callees)
 (fuel-mode--key ?d ?< 'fuel-show-callers)
 (fuel-mode--key ?d ?a 'fuel-autodoc-mode)
+(fuel-mode--key ?d ?p 'fuel-apropos)
 (fuel-mode--key ?d ?d 'fuel-help)
 (fuel-mode--key ?d ?e 'fuel-stack-effect-sexp)
 (fuel-mode--key ?d ?s 'fuel-help-short)
diff --git a/misc/fuel/fuel-syntax.el b/misc/fuel/fuel-syntax.el
index 8234f9fcc8..036ac7cbd0 100644
--- a/misc/fuel/fuel-syntax.el
+++ b/misc/fuel/fuel-syntax.el
@@ -301,21 +301,9 @@
   (funcall fuel-syntax--current-vocab-function))
 
 (defun fuel-syntax--find-in ()
-  (let* ((vocab)
-         (ip
-          (save-excursion
-            (when (re-search-backward fuel-syntax--current-vocab-regex nil t)
-              (setq vocab (match-string-no-properties 1))
-              (point)))))
-    (when ip
-      (let ((pp (save-excursion
-                  (when (re-search-backward fuel-syntax--sub-vocab-regex ip t)
-                    (point)))))
-        (when (and pp (> pp ip))
-          (let ((sub (match-string-no-properties 1)))
-            (unless (save-excursion (search-backward (format "%s>" sub) pp t))
-              (setq vocab (format "%s.%s" vocab (downcase sub))))))))
-    vocab))
+  (save-excursion
+    (when (re-search-backward fuel-syntax--current-vocab-regex nil t)
+      (match-string-no-properties 1))))
 
 (make-variable-buffer-local
  (defvar fuel-syntax--usings-function 'fuel-syntax--find-usings))
@@ -323,13 +311,19 @@
 (defsubst fuel-syntax--usings ()
   (funcall fuel-syntax--usings-function))
 
-(defun fuel-syntax--find-usings ()
+(defun fuel-syntax--find-usings (&optional no-private)
   (save-excursion
     (let ((usings))
       (goto-char (point-max))
       (while (re-search-backward fuel-syntax--using-lines-regex nil t)
         (dolist (u (split-string (match-string-no-properties 1) nil t))
           (push u usings)))
+      (goto-char (point-min))
+      (when (and (not no-private)
+                 (re-search-forward "\\_<<PRIVATE\\_>" nil t)
+                 (re-search-forward "\\_<PRIVATE>\\_>" nil t))
+        (goto-char (point-max))
+        (push (concat (fuel-syntax--find-in) ".private") usings))
       usings)))
 
 
diff --git a/misc/fuel/fuel-xref.el b/misc/fuel/fuel-xref.el
index be976a5392..31f8bcb69b 100644
--- a/misc/fuel/fuel-xref.el
+++ b/misc/fuel/fuel-xref.el
@@ -1,6 +1,6 @@
 ;;; fuel-xref.el -- showing cross-reference info
 
-;; Copyright (C) 2008 Jose Antonio Ortega Ruiz
+;; Copyright (C) 2008, 2009 Jose Antonio Ortega Ruiz
 ;; See http://factorcode.org/license.txt for BSD license.
 
 ;; Author: Jose Antonio Ortega Ruiz <jao@gnu.org>
@@ -75,11 +75,10 @@ cursor at the first ocurrence of the used word."
 (defvar fuel-xref--help-string "(Press RET or click to follow crossrefs)")
 
 (defun fuel-xref--title (word cc count)
-  (let ((cc (if cc "using" "used by")))
-    (put-text-property 0 (length word) 'font-lock-face 'bold word)
-    (cond ((zerop count) (format "No known words %s %s" cc word))
-          ((= 1 count) (format "1 word %s %s:" cc word))
-          (t (format "%s words %s %s:" count cc word)))))
+  (put-text-property 0 (length word) 'font-lock-face 'bold word)
+  (cond ((zerop count) (format "No known words %s %s" cc word))
+        ((= 1 count) (format "1 word %s %s:" cc word))
+        (t (format "%s words %s %s:" count cc word))))
 
 (defun fuel-xref--insert-ref (ref)
   (when (and (stringp (first ref))
@@ -124,12 +123,17 @@ cursor at the first ocurrence of the used word."
 (defun fuel-xref--show-callers (word)
   (let* ((cmd `(:fuel* (((:quote ,word) fuel-callers-xref))))
          (res (fuel-eval--retort-result (fuel-eval--send/wait cmd))))
-    (fuel-xref--fill-and-display word t res)))
+    (fuel-xref--fill-and-display word "using" res)))
 
 (defun fuel-xref--show-callees (word)
   (let* ((cmd `(:fuel* (((:quote ,word) fuel-callees-xref))))
          (res (fuel-eval--retort-result (fuel-eval--send/wait cmd))))
-    (fuel-xref--fill-and-display word nil res)))
+    (fuel-xref--fill-and-display word "used by" res)))
+
+(defun fuel-xref--apropos (str)
+  (let* ((cmd `(:fuel* ((,str fuel-apropos-xref))))
+         (res (fuel-eval--retort-result (fuel-eval--send/wait cmd))))
+    (fuel-xref--fill-and-display str "containing" res)))
 
 
 ;;; Xref mode:
@@ -138,7 +142,6 @@ cursor at the first ocurrence of the used word."
   (let ((map (make-sparse-keymap)))
     (suppress-keymap map)
     (set-keymap-parent map button-buffer-map)
-    (define-key map "q" 'bury-buffer)
     map))
 
 (defun fuel-xref-mode ()