Remember that we have an unseen audience. I try to keep the dialog informative even if I err on the side of stating the obvious to some of us.
Anyway Peter, the mouse/ball sprite goes out of sync with the actual cursor in the y axis, when the window is resized or made full-screen. I believe this effect can be eliminated by recalculating the x y metrics dynamically before each frame is generated.
This is what I do with Opengl Viewports - and also constrain the y/x proportion so that objects remain in proportion when the main window is stretched to a different shape.
Charles