function StartPainting(BmpX, BmpY: Integer): TRect;
Description
Start a programmatic retouch operation (i.e. to mimic a user a retouch operation with your own code).
Result is the area that was painted (in screen coordinates).
Normally, retouch operations are performed by the user via miRetouchTool, but it can be performed with code using:
1. Start retouching using StartPainting
2. Add extra points to the retouching operation using AddToPainting (Optional)
3. Enact the retouching changes using EndPainting