List and Piano do shattering properly

artist/pattern.go

@@ -20,7 +20,7 @@ func Fill (destination canvas.Canvas, source Pattern) (updated image.Rectangle)
 	return destination.Bounds()
 }
 
-// Draw lets you draw several subsets of 
+// DrawClip lets you draw several subsets of a pattern at once.
 func DrawClip (
 	destination canvas.Canvas,
 	source      Pattern,

elements/basic/list.go

@@ -461,5 +461,5 @@ func (element *List) draw () {
 	).Add(innerBounds.Min).Intersect(innerBounds)
 	pattern := element.theme.Pattern(theme.PatternSunken, state)
 	artist.DrawShatter (
-		element.core, pattern, covered)
+		element.core, pattern, bounds, covered)
 }

elements/fun/piano.go

@@ -305,7 +305,7 @@ func (element *Piano) draw () {
 	
 	pattern := element.theme.Pattern(theme.PatternPinboard, state)
 	artist.DrawShatter (
-		element.core, pattern, element.contentBounds)
+		element.core, pattern, element.Bounds(), element.contentBounds)
 }
 
 func (element *Piano) drawFlat (