Cursor jitter issue


I’m working on Salto (the simulator for the Xerox Alto) which uses SDL
to emulate the bitmap display and mouse on the Alto.

I’m seeing the following issue: when I don’t update the coordinates of
the cursor, I still see in cursor bobbing up and down by a few pixels…
occasionally by a hundred pixels or so.

Not sure why.

At first I thought this was a side-effect of the “SDL_ShowCursor() warp
cursor” feature described by Zoltan here:

I’m running SDL-1.2.13-11.fc12.x86_64 on Fedora 12, a Phenom box (x86_64).

I’ll try building on MacOS (if possible) and see if the problem exists
there, too.