In normal use, the entire graphics is visible in the client area. It's not too usable otherwise. This is just to handle the possibility
that the client area has been reduced. It's possible that a mouse click in the client area could cause changes to occur that need
updating, just as in the full size display. The bitmap image is completely updated. And then whatever part of the bitmap happens
to visible in the client area gets updated too.
I'm not using scoll bars, or any other means of moving the client "window" around over the full size bitmap image. The upper left
corner of the client area always corresponds to the upper left corner of the bitmap.
I tried displaying the coordinates in the PAINTSTRUCT, ps.rcPaint, each time WM_PAINT message comes in. But it's not working right.
So I have to fix that. The values ought to change each time the window is enlarged or covered and then uncovered. They don't.
And that's strange, because the bitblt, which uses the same coordinates does work.
