Thought this might be useful to the devs.

1. Create photo document
2. Import image
3. Activate "Mask mode"
4. Draw a closed shape
5. Draw a second closed shape inside the first shape
6. "Combine Shapes" -> "Substract Shapes" (I would have expected the top shape to create a hole in the mask created by the bottom shape, like in does with "manual mask mode" ;-), but this does not work)
7. Undo
8. Serious Error from Xtreme - Access Violation exception at 0x00000000