If it doesn't queue a redraw and allow the backend to clear and swap
the buffers then the results will be skewed because it is not
predictable when the driver will actually render the scene.
- Fix a typo in a for loop in create_label which left 'i'
uninitialised and caused a crash if you're unlucky.
- Set the CLUTTER_VBLANK=none environment variable.
- Don't quit on a keypress.
- Trailing whitespace tidy up.
