[SDL] OpenGL viewport issue

[Brad]

I've got a weird issue. If I create a window with a height of 768 (which 
happens to be my desktop resolution) or something close to it (like > 
760) the viewport isn't quite right. For example, I have a FPS counter 
in the upper left corner of the screen, but when the game starts up the 
counter is too high, like the top portion of it is underneath the 
titlebar. The higher I set the window height the higher the counter is, 
until it isn't visible anymore. BUT as soon as I move the window and 
release the mouse button the viewport "pops" to what it should be. I 
don't have this issue in fullscreen mode, or lower window sizes, like 
800x600.

This is on Windows with SDL 1.2.13. Any ideas what could be wrong?