The idea is to warn the user that changing the settings might break
the setup when we know it could be dangerous. The following cases are
considered:
* Scale filter Accurate
* Tearing prevention
* keep window thumbnail always
* EGL if EGL and GLX are available
* unredirect fullscreen not working on all hardware
In addition the OpenGL is Unsafe warning is turned int a KMessageWidget
which is also used for all the other warnings.
REVIEW: 118494
For a classic user interface like the advanced compositor settings the
good old widgets are still better suited than the new QuickControls.
REVIEW: 118273
