Hi Michael,

I have revealed strange bug...

- draw circle (or rectangle, polygon...)
- mirror it
- draw third circle so it intersects the previous ones
- try doing a boolean-union operation between all circles



It doesn't work unless you:
- use history mechanism (it means e.g. moving the original circle)
- break history of mirrored copy
- draw bigger circle before mirroring the small one
- boolean it piece-by-piece
- ...

Petr