When I run the following code, I start to get  MNU: 
UndefinedObject>>containsPoint   errors.

http://pastebin.com/TTDmSnZS

The errors show up with Intel Macs running Mac OS X 19.6.8 using  Squeak 
4.2 all-in-one, Cog with Squeak4.2-10966 and CogMT2489 and Cog2489 with 
both Squeak 4.3alpha-11314 and Squeak4.3alpha11636.

In order to get the errors open Squeak, open a workspace and transcript 
and paste teh above code into the workspace. Select the part above the 
"++++++++...+++++++" and do-it

then select the part within  the two comments (myGrid delete. Smalltalk 
garbageCollect) and do-it.

then iterate manually with i = 2 through 10 and evaluate the lower half 
of the code (below the comments)

Eventually you get one or more MNU: UndefinedObject>>containsPoint  errors


When I do THIS code: http://pastebin.com/Mp0aZLUj

the errors seem to go away, but the overhead of the 1000+ GC calls is 
way too much.

Suggestions? I was testing to see if I could prototype a 2D shooter in 
Squeak using morphs for the bitmaps when the bug showed up.

Thanks.


Lawson