The recent issue with form sliding was reported here: http://code.google.com/p/pharo/issues/detail?id=5568 - Francisco On 11 May 2012 02:40, Chris Muller <asqueaker@gmail.com> wrote:

Don't have any info but I observed this problem in Squeak a couple of times doing the exact same thing -- dragging a form outside window bounds.

On Thu, May 10, 2012 at 4:21 PM, Igor Stasenko <siguctua@gmail.com> wrote:

...

remember the recent issue with form sliding? It strikes again.. i dragged my window outside of OS window bounds and then released the button..

i'm not sure if this a VM issue or image/side.. but i think VM has to be blamed, because it should do range checking before accepting requests for doing stupid operations, like blitting outside the buffer :)

Luckily i were running debug version of VM and under debugger doing things completely unrelated to this :)

Here some info about crash point:

Program received signal EXC_BAD_ACCESS, Could not access memory. Reason: KERN_PROTECTION_FAILURE at address: 0x0000000a 0x00034949 in longAtPointer (ptr=0xa <Address 0xa out of bounds>) at sqMemoryAccess.h:81 81 static inline sqInt longAtPointer(char *ptr) { return *(sqInt *)ptr; } (gdb) bt #0 0x00034949 in longAtPointer (ptr=0xa <Address 0xa out of bounds>) at sqMemoryAccess.h:81 #1 0x00034969 in longAt (oop=10) at sqMemoryAccess.h:98 #2 0x0003a1c0 in ceSendsupertonumArgs (selector=525641856, superNormalBar=0, rcvr=10, numArgs=0) at /Users/sig/projects/cog/sig-cog/src/vm/gcc3x-cointerp.c:10729 #3 0x1f40005c in ?? () #4 0x00049045 in initStackPagesAndInterpret () at /Users/sig/projects/cog/sig-cog/src/vm/gcc3x-cointerp.c:17865 #5 0x00026ad1 in interpret () at /Users/sig/projects/cog/sig-cog/src/vm/gcc3x-cointerp.c:1979

(gdb) call printCallStack() 0xbff5dc80 M [] in Form(DisplayObject)>slideFrom:to:nSteps:delay: 578564724: a(n) Form 0xbff5dcc4 I Form(DisplayObject)>follow:while:bitsBehind:startingLoc: 578564724: a(n) Form 0xbff5dcfc I Form(DisplayObject)>follow:while: 578564724: a(n) Form 0xbff5dd2c I Form(DisplayObject)>slideFrom:to:nSteps:delay: 578564724: a(n) Form 0xbff5dd78 I NautilusWindow(Morph)>slideBackToFormerSituation: 565212772: a(n) NautilusWindow 0xbff5dd9c I NautilusWindow(Morph)>rejectDropMorphEvent: 565212772: a(n) NautilusWindow 0xbff5ddc8 I HandMorph>dropMorph:event: 535318276: a(n) HandMorph 0xbff5ddf4 I [] in HandMorph>dropMorphs: 535318276: a(n) HandMorph 0xbff5de14 M Array(SequenceableCollection)>reverseDo: 578544144: a(n) Array 0xbff5de38 I HandMorph(Morph)>submorphsReverseDo: 535318276: a(n) HandMorph 0xbff5de5c I HandMorph>dropMorphs: 535318276: a(n) HandMorph 0xbff5de80 M HandMorph>handleEvent: 535318276: a(n) HandMorph 0xbff5deac M HandMorph>processEvents 535318276: a(n) HandMorph 0xbff5dec4 M [] in WorldState>doOneCycleNowFor: 526955120: a(n) WorldState 0xbff5dee8 M Array(SequenceableCollection)>do: 525348844: a(n) Array 0xbff5df04 M WorldState>handsDo: 526955120: a(n) WorldState 0xbff5df20 M WorldState>doOneCycleNowFor: 526955120: a(n) WorldState 0xbff5df3c M WorldState>doOneCycleFor: 526955120: a(n) WorldState 0xbff5df58 M PasteUpMorph>doOneCycle 526861788: a(n) PasteUpMorph 0xbff5df70 M [] in MorphicUIManager>spawnNewProcess 526984156: a(n) MorphicUIManager

i think best solution right now is to avoid using sliding (NautilusWindow(Morph)>slideBackToFormerSituation:). for a longer term, a best solution is to fix this issue, of course :)

-- Best regards, Igor Stasenko.