Comment 2 for bug 755127

StacktraceTop:
 __pthread_mutex_lock (mutex=0x7) at pthread_mutex_lock.c:50
 g_source_unref_internal (source=0xae0f2f8, context=0x3, have_lock=0) at /build/buildd/glib2.0-2.28.5/./glib/gmain.c:1671
 Glib::Source::unreference (this=0x9df7b80) at main.cc:765
 ~RefPtr (this=0x9da5540, __in_chrg=<value optimized out>) at /usr/include/glibmm-2.4/glibmm/refptr.h:207
 PrivateScreen::~PrivateScreen (this=0x9da5540, __in_chrg=<value optimized out>) at /build/buildd/compiz-0.9.4+bzr20110407/src/screen.cpp:4882