fix incremental layout regression

TODO.FACTOR.txt

@@ -1,4 +1,3 @@
-- finish scrollbars
 - fix up the min thumb size hack
 
 + ui:

library/ui/gadgets.factor

@@ -60,27 +60,14 @@ DEFER: add-invalid
         [ gadget-parent [ relayout ] when* ] ifte
     ] ifte ;
 
-: (relayout-down)
-    dup invalidate gadget-children [ (relayout-down) ] each ;
-
 : relayout-down ( gadget -- )
     #! Relayout a gadget and its children.
-    dup add-invalid (relayout-down) ;
+    dup add-invalid invalidate ;
 
 : set-gadget-dim ( dim gadget -- )
     2dup rect-dim =
     [ 2drop ] [ [ set-rect-dim ] keep relayout-down ] ifte ;
 
-GENERIC: pref-dim ( gadget -- dim )
-
-M: gadget pref-dim rect-dim ;
-
-GENERIC: layout* ( gadget -- )
-
-: prefer ( gadget -- ) dup pref-dim swap set-gadget-dim ;
-
-M: gadget layout* drop ;
-
 GENERIC: user-input* ( ch gadget -- ? )
 
 M: gadget user-input* 2drop t ;

library/ui/layouts.factor

@@ -4,6 +4,16 @@ IN: gadgets-layouts
 USING: errors gadgets generic hashtables kernel lists math
 matrices namespaces sdl sequences ;
 
+GENERIC: pref-dim ( gadget -- dim )
+
+M: gadget pref-dim rect-dim ;
+
+GENERIC: layout* ( gadget -- )
+
+M: gadget layout* drop ;
+
+: prefer ( gadget -- ) dup pref-dim swap set-gadget-dim ;
+
 : layout ( gadget -- )
     #! Set the gadget's width and height to its preferred width
     #! and height. The gadget's children are laid out first.