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Florian H
ktikz - Editor for the TikZ language Graphics
I have the same problem with ktikz (from svn) here on Ubuntu 8.04. The problem appears right after the main window appears. Running ktikz from gdb gives following:

ktikz: ../../src/xcb_lock.c:77: _XGetXCBBuffer: Assertion `((int) ((xcb_req) - (dpy->request)) >= 0)' failed.

Program received signal SIGABRT, Aborted.
[Switching to Thread 0xb6c85720 (LWP 23839)]
0xb7ef9410 in __kernel_vsyscall ()
(gdb) backtrace
#0 0xb7ef9410 in __kernel_vsyscall ()
#1 0xb721a085 in raise () from /lib/tls/i686/cmov/libc.so.6
#2 0xb721ba01 in abort () from /lib/tls/i686/cmov/libc.so.6
#3 0xb721310e in __assert_fail () from /lib/tls/i686/cmov/libc.so.6
#4 0xb6ff6324 in _XGetXCBBuffer () from /usr/lib/libX11.so.6
#5 0xb6ff75f3 in _XSend () from /usr/lib/libX11.so.6
#6 0xb6ff7758 in _XEventsQueued () from /usr/lib/libX11.so.6
#7 0xb6fe0a4f in XEventsQueued () from /usr/lib/libX11.so.6
#8 0xb77901aa in ?? () from /usr/lib/libQtGui.so.4
#9 0x080f8f10 in ?? ()
#10 0x00000002 in ?? ()
#11 0xb6f00248 in ?? () from /usr/lib/libglib-2.0.so.0
#12 0xb7790170 in ?? () from /usr/lib/libQtGui.so.4
#13 0xb6f00248 in ?? () from /usr/lib/libglib-2.0.so.0
#14 0xbfc1c738 in ?? ()
#15 0xb6e8a3e0 in g_main_context_prepare () from /usr/lib/libglib-2.0.so.0
Backtrace stopped: previous frame inner to this frame (corrupt stack?)


But personally I think the problem is different to the backtrace message. I think it's some kind of thread synchronization problem when updating the preview window. If I comment out following lines from ktikz.cpp

connect(m_tikzEditorView, SIGNAL(contentsChanged()),
m_tikzController, SLOT(regeneratePreview()));

ktikz runs but (of course) is not working properly.

Trying different breakpoints did not help. Either the program was working correctly (with a preview) or it crashed in random pieces of code.

Any ideas?
May 06 2008