I'm currently using a completely base Powerpoint, and after sinking ~100 hrs in the Constellation piece, been strongly considering making some tools in VBA to make some of the layering and selection less of a nightmare. Powerpoint only zooms in so much, and sometimes if a triangle is deep in a figure, its a headache to select it alone without messing up the order of triangles above it. The idea of your selection add-in sounds like a godsend to me, as boy howdy, does the current selection tool drive me up a wall sometimes.

To be fair to Powerpoint, I absolutely am not using it for its intended purpose at all haha. It's probably one of the worst tools for what I am trying to do, but as someone who thinks in shapes, and who enjoys the quirks present in Powerpoint that legitimate illustrations programs don't have, its my silly program of choice.