This example implements a BaseTransform subclass, which overlays
a video with a moving line and which reacts on navigation events
and paints a circle at the position where a mouse button 1 was pressed.
glib-sharp will only get a new release with the new API that we need for
3.0 in a year or something. Instead of waiting a year before we can release
something we now have our own internal copy of glib-sharp trunk that will
be dropped once glib-sharp 3.0 is released.
Everything is now compilable and working without any additional patches.