Ignore spurious BadMatch errors which can occur when autologon is enabled

The errors originate from this commit http://lists.kde.org/?l=kde-commits&m=107824396401206&w=2 and appear only on certain hardware/software combinations
(cherry picked from commit 2a889fe314)

kdm/kfrontend/kgapp.cpp

@@ -495,7 +495,11 @@ kg_main( const char *argv0 )
 	UnsecureDisplay( dpy );
 	restore_modifiers();
 
+	// Qt4 has a nasty habit of generating BadWindow errors in normal operation, so we simply ignore them
+	// This also prevents the user from being dropped to a console login if Xorg glitches or is buggy
+	XSetErrorHandler( ignoreXError );
 	XSetInputFocus( qt_xdisplay(), PointerRoot, PointerRoot, CurrentTime );
+	XSetErrorHandler( (XErrorHandler)0 );
 
 	delete app;
 }