If a QPainter is created on a device after QApplication setup and then ended after the QApplication is torn down,
Qt crashes if using the X11 engine but not the raster engine.

{{
#include <QtGui/QApplication>
#include <QtGui/QPainter>
#include <QtGui/QPixmap>

int main(int argc, char** argv)
{
	QPixmap* pixmap;
	QPainter* painter;
	{
		QApplication app(argc,argv);
		painter = new QPainter;
		pixmap = new QPixmap(100,100);
		painter->begin(pixmap);
	}
	painter->end();
}
}}

This bug report was distilled from a more complex issue involving <canvas> in WebKit and garbage collection. I am unsure if the code above should be considered legitimate or not (in other words, is the crash here an unexpected bug in Qt?). In QtWebKit, a QPainter is created for WebCore::ImageBufferData which may be active until it is destroyed during garbage collection which may happen right at the end of ~QApplication when the WebCore::SharedTimerQt singleton is destroyed, if there is a WebKit GC cycle pending. The attached test case project triggers this case when used with Qt 4.6 / X11. I did not experience a crash when using a Qt trunk build but that uses the raster engine by default.