Exciting new release (download migensystem-1-2385a.zip) that includes an implementation of tiles with negative colours. Turn these tiles into a pattern and add them on top of any overlaps you have. The overlaps are ‘erased‘ !
To colour your patterns in the parallel world, you need to subtract the number of tiles of a negative coloured pattern from the total number of positively colour tiles. Confusing ? It may be, but the functionality provides an opportunity for interesting discussions with students.
What do you think ?
This version also replaces completely the editing of expressions with the menu-driven editing.