Let say that i have id of another Xlib window and i want to draw over this window rectangle. Is there way to to draw it using Qt? I found on solution but it doesn't work for me:
QPixmap pix = QPixmap::fromX11Pixmap(wId, QPixmap::ExplicitlyShared);
pix.fill(QColor::fromRgb(255,255,255));
I expect it'll fill window with white color, but it doesn't.
You could embed this window, place an invisible window on top and render into this invisible window. The effect would be the same : a rectangle over the window.