From the self pointer in the call frame:
self=0xb7ca746e <-[NSView displayRectIgnoringOpacity:inContext:]+318>
gdb resolves this address to an address in the code of the displayRectIgnoringOpacity:inContext: method from the NSView class. :-)
Aha, interesting. But this still rings no bell (no idea how this could be).
This changed nothing. The program still crashes at the same spot and MapView is never deallocated (at least dealloc not called)!? And remember, the app works perfectly well in two other environments (for whatever that's worth).
With the same version of gnustep-base and gnustep-gui?
No, with current MacOSX and ancient GNUstep sources I was using so far on Solaris and Debian
I am now trying current GNUstep sources on Ubuntu 16, so almost everything has changed: gcc, objc, GNUstep, OS,... :-(
Thanks,
Andreas