问题
I've got a Qt application running on X with -graphicssystem opengl as a command line arg. Whenever I start a drag and drop operation (via QDrag::exec(), using native cursors and no custom drag pixmap), the screen flashes briefly with vertical stripes of what seems to be garbage data from the display buffer.
The application occupies the entirety of the touchscreen it displays on, and hence we aren't using a compositing window manager (though I get the same issue running from fluxbox). The problem does not occur in either situation if I'm not using OpenGL as the renderer.
Most strangely of all: the problem does not occur if my application window is anything other then a perfect fit for the screen - i.e. I could offset the window by 1 pixel from the top left corner, or make the window 1 pixel larger or smaller than the screen on either axis and the problem magically disappears.
Any ideas what might be causing this?
来源：https://stackoverflow.com/questions/9738835/starting-a-qt-drag-operation-on-x11-w-opengl-causes-screen-flicker