The OpenGL renderer isn't really useful right now, its not quite up
to date, its not really faster than software and it only supports a limited
subset of drivers. So, lets disable it for now.
Long term opengl rendering of the 2d part of spice is important if we want
to combine 2d and 3d rendering (say if spice adds opengl support in the
protocol). But until then this is isn't useful for normal use.
Screen now have to modes locked and unlocked.
In unlocked mode, the application can change screen size and so
reduce resolution changing. The application can also choose to
change window size while not in full screen mode.
In locked mode the application must ewtain locker screen size
setting.
Additional changes that were required for the feature:
1) focusing on the pointed window in full screen mode
2) In X11 - handling events that occur during keyboard ungrabbing
3) In X11 - handling Leave/Enter Notify events that occur during keyboard grabbing/ungrabbing
4) In X11 - fix for focus events that are handled in the wrong order (happens when
focus events occur during grabbing the keyboard)
5) In X11 - ignoring key release events during key holding
6) In Windows - synchronizing keyboard release events that occured during a modal loop
