ui.gadgets.grid-lines: fix rough edges on right and bottom.

basis/ui/gadgets/grid-lines/grid-lines.factor

@@ -13,8 +13,8 @@ C: <grid-lines> grid-lines
 :: (compute-grid-lines) ( grid n ns orientation -- seq )
     grid gap>> :> gap
     ns n suffix gap orientation v. '[ _ - orientation n*v ] map
-    dup grid dim>> gap v- orientation reverse [ v* ] keep '[ _ _ v+ v+ ] map
-    [ [ gap [ 2/ ] map v+ ] map ] bi@ zip ;
+    dup grid dim>> gap v- orientation reverse v* '[ _ v+ ] map
+    gap [ 2 /f ] map '[ [ _ v+ ] map ] bi@ zip ;
 
 : compute-grid-lines ( grid -- lines )
     dup <grid-layout>