Fix some minor UI bugs

basis/ui/gadgets/line-support/line-support.factor

@@ -30,6 +30,9 @@ M: line-gadget line-height font>> font-metrics height>> ceiling ;
 : validate-line ( m gadget -- n )
     control-value [ drop f ] [ length 1- min 0 max ] if-empty ;
 
+: valid-line? ( n gadget -- ? )
+    control-value length 1- 0 swap between? ;
+
 : visible-line ( gadget quot -- n )
     '[
         [ clip get @ origin get [ second ] bi@ - ] dip

basis/ui/gadgets/scrollers/scrollers.factor

@@ -58,6 +58,7 @@ M: viewport pref-dim* gadget-child pref-viewport-dim ;
     {
         [ scroller-value vneg offset-rect ]
         [ viewport>> dim>> rect-min ]
+        [ viewport>> loc>> offset-rect ]
         [ viewport>> [ v- { 0 0 } vmin ] [ v- { 0 0 } vmax ] with-rect-extents v+ ]
         [ scroller-value v+ ]
         [ scroll ]

basis/ui/gadgets/tables/tables.factor

@@ -261,19 +261,20 @@ M: table model-changed
     row-rect [ { 0 1 } v* ] change-dim ;
 
 : (select-row) ( table n -- )
-    [ dup [ [ thin-row-rect ] [ drop ] 2bi scroll>rect ] [ 2drop ] if ]
+    [ dup [ [ thin-row-rect dup unparse show ] [ drop ] 2bi scroll>rect ] [ 2drop ] if ]
     [ >>selected-index relayout-1 ]
     2bi ;
 
 : mouse-row ( table -- n )
     [ hand-rel second ] keep y>line ;
 
+: if-mouse-row ( table true: ( table mouse-index -- ) false: ( table -- ) -- )
+    [ [ mouse-row ] keep 2dup valid-line? ]
+    [ ] [ '[ nip @ ] ] tri* if ; inline
+
 : table-button-down ( table -- )
     dup takes-focus?>> [ dup request-focus ] when
-    dup control-value empty? [ drop ] [
-        dup [ mouse-row ] keep validate-line
-        [ >>mouse-index ] [ (select-row) ] bi
-    ] if ;
+    [ swap [ >>mouse-index ] [ (select-row) ] bi ] [ drop ] if-mouse-row ;
 
 PRIVATE>
 
@@ -283,11 +284,14 @@ PRIVATE>
     [ 2drop ]
     if ;
 
+: row-action? ( table -- ? )
+    [ [ mouse-row ] keep valid-line? ]
+    [ single-click?>> hand-click# get 2 = or ] bi and ;
+
 <PRIVATE
 
 : table-button-up ( table -- )
-    dup single-click?>> hand-click# get 2 = or
-    [ row-action ] [ update-selected-value ] if ;
+    dup row-action? [ row-action ] [ update-selected-value ] if ;
 
 : select-row ( table n -- )
     over validate-line
@@ -320,13 +324,6 @@ PRIVATE>
 : next-page ( table -- )
     1 prev/next-page ;
 
-: valid-row? ( row table -- ? )
-    control-value length 1- 0 swap between? ;
-
-: if-mouse-row ( table true false -- )
-    [ [ mouse-row ] keep 2dup valid-row? ]
-    [ ] [ '[ nip @ ] ] tri* if ; inline
-
 : show-mouse-help ( table -- )
     [
         swap