This is a fix for the "very old buglet" reported by Bob Arning. I'd appreciate
if someone could review this before I move it to trunk, as it may have performance
implications.

Dave

On Sun, Jan 13, 2013 at 06:49:13PM +0000, commits at source.squeak.org wrote:
> A new version of Morphic was added to project The Inbox:
> http://source.squeak.org/inbox/Morphic-dtl.634.mcz
> 
> ==================== Summary ====================
> 
> Name: Morphic-dtl.634
> Author: dtl
> Time: 13 January 2013, 1:48:33.942 pm
> UUID: 02716c40-7437-458c-80ff-22679fcd3c04
> Ancestors: Morphic-dtl.633
> 
> Fix for Morphic layout bug reported by Bob Arning in http://lists.squeakfoundation.org/pipermail/squeak-dev/2013-January/167757.html
> 
> Invalidate changed regions in Morph>>layoutBounds: in the same manner as in Morph>>doLayoutIn:
> 
> =============== Diff against Morphic-dtl.633 ===============
> 
> Item was changed:
>   ----- Method: Morph>>layoutBounds: (in category 'layout') -----
>   layoutBounds: aRectangle
>   	"Set the bounds for laying out children of the receiver.
>   	Note: written so that #layoutBounds can be changed without touching this method"
> + 	| priorBounds outer inner box |
> + 	priorBounds := self outerBounds.
> - 	| outer inner |
>   	outer := self bounds.
>   	inner := self layoutBounds.
>   	bounds := aRectangle origin + (outer origin - inner origin) corner:
> + 				aRectangle corner + (outer corner - inner corner).
> + 	box := self outerBounds.
> + 	box = priorBounds 
> + 		ifFalse: [self invalidRect: (priorBounds quickMerge: box)]!
> - 				aRectangle corner + (outer corner - inner corner).!
>