Thanks for sharing Tanuki, I'll look into getting that turned on automatically.
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In other news:
The mouse trails are caused by HEL's Flip method not flipping!
HEL's Flip (apparently) just Blts the back buffer to the front buffer,
The front buffer is discarded/overwritten and is never flipped/swapped to the back buffer.
The game tries to perform a minimum screen update by erasing the mouse cursor from the back buffer.
However the game doesn't realize that the front buffer isn't being returned to the back buffer...
A fix like the following seems like it would be slow because its copying the entire screen three times instead of once.
pDDSOffscreen->BltFast( 0, 0, pDDSFront, NULL, DDBLTFAST_NOCOLORKEY | DDBLTFAST_WAIT );
pDDSFront->BltFast( 0, 0, pDDSBack, NULL, DDBLTFAST_NOCOLORKEY | DDBLTFAST_WAIT ); // <- basically what Flip is doing
pDDSBack->BltFast( 0, 0, pDDSOffscreen, NULL, DDBLTFAST_NOCOLORKEY | DDBLTFAST_WAIT );
any ideas are welcome