Assertion failure in -[NSNextStepFrame lockFocus]

FROM : Apparao Mulpuri
DATE : Wed May 14 15:30:20 2008

HI,

  I have a Cocoa based multi monitor application,which will run on
Mac OS X 10.3.9 onwards.

  It is working as expected in 10.3.9  and Tiger os versions. But, in
Leopard 10.5.2, its giving following exception:

** Assertion failure in -[NSNextStepFrame lockFocus],
/SourceCache/AppKit/AppKit-949.27/AppKit.subproj/NSView.m:4751
May 14 17:37:39 apparao-power-mac-g5 MyCocoaApp[123]:
-[NSNextStepFrame(0x143610) lockFocus] failed with window=0x142e60,
windowNumber=62, [self isHiddenOrHasHiddenAncestor]

  For single monitor with Leopard its working fine. With secondary
monitor, its throwing above exception. In Secondary monitor case, i am
doing window(which is custom class of NSWindow and created in IB) copy
operation(using achieving and unarchieving) and displaying it on
secondary monitor.

  I am not getting any idea from the above exception. By google, i
found that, some one is experienced the same exception with custom
window creation on Leopard.

  Any pointers on this is really appreciated.

Thanks,
- Apparao.