Still don't see a program coding limitation and yet still (now P21), as a user, we have no indicator if 'define pattern' is active or not unless we place a mark across the canvas edge.
Why not Corel? simply add a check mark or icon display of 'on' vs 'off ' ?
So my suggestion (again) is to add it as a feature...at a minimum, simply make it an optional display if some do not use or want to see it and be aware.
And make it obvious instead of buried in menus.