Stopped waiting for IceX updates and bought Earthsculptor which has a undo button. Don't know if there will be a update to IceX2 soon? Guess the planned new features are harder to get working bugfree then expected by the developer.

Did like the way IceX operated, but it had some problems back then with visible seams and also textures on slope areas don't really look good. Maybe that is to be solved with a custom shader or by making the slopes less steep though.