Windows are shown in xcb plugin without show() being called

Apply following patch to examples/gui/rasterwindow:

diff --git a/examples/gui/rasterwindow/main.cpp b/examples/gui/rasterwindow/main.cpp
index f34a419..331f329 100644
— a/examples/gui/rasterwindow/main.cpp
+++ b/examples/gui/rasterwindow/main.cpp
@@ -48,6 +48,11 @@ int main(int argc, char **argv)
RasterWindow window;
window.show();

+ QWindow hiddenWindow;
+ hiddenWindow.resize(400, 300);
+ hiddenWindow.create();
+ hiddenWindow.setTitle("Should not be shown");
+
return app.exec();
}
//! [1]

The window should not be shown since we only call create(). However, it ends up getting shown, typically after a couple of seconds. The bug is caused by b5bdd31de41cb5e6d6abedce79864fc01d8d4984, which does xcb_map_window on the window for some reason. Presumably that means the X window receives a property notify on QXcbAtom::_XEMBED_INFO with the XEMBED_MAPPED bit set.