Under Ubuntu 13.04, on a Dell XPS laptop with hybrid graphics (only Intel HD3000 drivers currently running):

On transitioning from Qt 5.02 to Qt 5.1, all QtQuick apps that used to work just fine, start to show severe flickering.

It happens mostly under graphics load, but random flickering of the entire window (even the header of the window with the close button) appears at applications that simply comprise a bunch of QML Controls.