kripton@ayanta ~ $ gdb qtdemo                                                                                                                                                                                        
GNU gdb (Gentoo 7.4 p1) 7.4                                                                                                                                                                                          
Copyright (C) 2012 Free Software Foundation, Inc.                                                                                                                                                                    
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>                                                                                                                                        
This is free software: you are free to change and redistribute it.                                                                                                                                                   
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"                                                                                                                                           
and "show warranty" for details.                                                                                                                                                                                     
This GDB was configured as "x86_64-pc-linux-gnu".                                                                                                                                                                    
For bug reporting instructions, please see:                                                                                                                                                                          
<http://bugs.gentoo.org/>...                                                                                                                                                                                         
Reading symbols from /usr/bin/qtdemo...(no debugging symbols found)...done.
(gdb) run
Starting program: /usr/bin/qtdemo 
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".
[New Thread 0x7fffe72ca700 (LWP 22228)]
[Thread 0x7fffe72ca700 (LWP 22228) exited]
[New Thread 0x7fffe72ca700 (LWP 22232)]
X Error: BadMatch (invalid parameter attributes) 8
  Major opcode: 1 (X_CreateWindow)
  Resource id:  0x156
X Error: BadWindow (invalid Window parameter) 3
  Major opcode: 3 (X_GetWindowAttributes)
  Resource id:  0x6a00004

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff35c8240 in XVisualIDFromVisual () from /usr/lib64/libX11.so.6
(gdb) bt
#0  0x00007ffff35c8240 in XVisualIDFromVisual () from /usr/lib64/libX11.so.6
#1  0x00007ffff65b034e in ?? () from /usr/lib64/qt4/libQtGui.so.4
#2  0x00007ffff65b03f0 in ?? () from /usr/lib64/qt4/libQtGui.so.4
#3  0x00007ffff65b327c in QWidgetPrivate::create_sys(unsigned long, bool, bool) () from /usr/lib64/qt4/libQtGui.so.4
#4  0x00007ffff6563cad in QWidget::create(unsigned long, bool, bool) () from /usr/lib64/qt4/libQtGui.so.4
#5  0x00007ffff6b9b4be in QEgl::createSurface(QPaintDevice*, void*, QEglProperties const*) () from /usr/lib64/qt4/libQtGui.so.4
#6  0x00007ffff70eadf8 in QGLContext::chooseContext(QGLContext const*) () from /usr/lib64/qt4/libQtOpenGL.so.4
#7  0x00007ffff7075f2f in QGLContext::create(QGLContext const*) () from /usr/lib64/qt4/libQtOpenGL.so.4
#8  0x00007ffff70e9b05 in QGLWidget::setContext(QGLContext*, QGLContext const*, bool) () from /usr/lib64/qt4/libQtOpenGL.so.4
#9  0x00007ffff707626c in ?? () from /usr/lib64/qt4/libQtOpenGL.so.4
#10 0x00007ffff70e9bb2 in ?? () from /usr/lib64/qt4/libQtOpenGL.so.4
#11 0x00007ffff707707e in QGLWidget::QGLWidget(QWidget*, QGLWidget const*, QFlags<Qt::WindowType>) () from /usr/lib64/qt4/libQtOpenGL.so.4
#12 0x000000000042d0bb in ?? ()
#13 0x000000000042e1bf in ?? ()
#14 0x000000000040eb62 in ?? ()
#15 0x00007ffff534a22c in __libc_start_main () from /lib64/libc.so.6
#16 0x000000000040ea29 in ?? ()
#17 0x00007fffffffd8a8 in ?? ()
#18 0x000000000000001c in ?? ()
#19 0x0000000000000001 in ?? ()
#20 0x00007fffffffdcba in ?? ()
#21 0x0000000000000000 in ?? ()
(gdb) q
A debugging session is active.

        Inferior 1 [process 22072] will be killed.

Quit anyway? (y or n) y