It might be desirable to add a client callback for
detecting a resolution change for the display.
Dan Torop submitted a freeglut patch that lets the
library pick up resolution changes on WIN32. On
WIN32, we could easily do a callback for that.
The patch to detect the resolution change was made to
OpenGLEAN this morning; as with Dan Torop's original
patch, it is passive (just update the global state).
On X, we may be forced to poll the X server everytime
that we want to know the (current) resolution.
In any case, it would be possible, at the bottom of
glutMainLoopEvent(), to check the resolution and if
it is different, dispatch a client callback.