When trying to keep a painting with the PaintBoxMorph I get this error
Karl

Image version: Squeak3.1alpha
latest update: #3987
Current Change Set: New Changes

VM version: nil
for: Mac OS

Receiver: a BitBlt

Instance variables: 
destForm: 	Form(800x1x1)
sourceForm: 	Form(800x600x16)
halftoneForm: 	nil
combinationRule: 	3
destX: 	0
destY: 	0
width: 	800
height: 	1
sourceX: 	0
sourceY: 	0
clipX: 	0
clipY: 	0
clipWidth: 	800
clipHeight: 	1
colorMap: 	a ColorMap

Method (temp) variables: 

Stack: 
BitBlt(Object)>>error:
BitBlt>>copyBits
[] in Form>>rectangleEnclosingPixelsNotOfColor:
[] in Interval(Collection)>>detect:ifNone:
Interval>>do:
Interval(Collection)>>detect:ifNone:
Form>>rectangleEnclosingPixelsNotOfColor:
SketchEditorMorph>>deliverPainting:evt:
SketchEditorMorph>>save:
SketchEditorMorph>>savePainting:evt:
PaintBoxMorph>>keep:with:evt:
[] in ThreePhaseButtonMorph>>doButtonAction:
BlockContext>>ensure:
CursorWithMask(Cursor)>>showWhile:
ThreePhaseButtonMorph>>doButtonAction:
ThreePhaseButtonMorph>>mouseUp:
ThreePhaseButtonMorph(Morph)>>handleMouseUp:
MouseButtonEvent>>sentTo:
ThreePhaseButtonMorph(Morph)>>handleEvent:
ThreePhaseButtonMorph(Morph)>>handleFocusEvent: