GTK on QNX and POSIX shared memory?

Has anyone tried using both GTK and the POSIX shared memory API in the
same piece of code? I’m using QNX 6.1.0/GTK 1.2.10 (from

I’m seeming some very strange behavior ranging from crashing the machine
hard (have to reboot, sometimes files get corrupted), to having
gtk_main() crash immediately after it starts.

I’ve been staring at the memory allocation calls to shm_open, mmap(),
and ftruncate(), and there doesn’t seem to be any obvious memory errors…

Anybody have any ideas as to what might be going on?