Port kwin away from connection() and rootWindow()
Under the hood, connection() looks up a property called x11Connection on the application object. A faster way to get a hold on the xcb_connection_t object is to use kwinApp()->x11Connection() directly without involving QObject's property machinery. Same with rootWindow() and kwinApp()->x11RootWindow().
Even though this task seems very trivial, it's not. We have a few of tests that initialize core X11 objects (the xcb connection and the roor window) by setting a couple of properties on the application object, see test_xcb_window.cpp. Also, xcbutils.h relies on connection() and rootWindow() quite a lot...
Edited by Vlad Zahorodnii