Gary, all, I am far from comfortable with Polymorph design and programming, but I have managed stick some controls on standard windows. Now I need to do something that would benefit from composition of an image and a selection mask into something that allows the mask to be edited while "scrubbing" over the image. Then those get paired, and then the pairs go into sequences. The pairing can be done with tabs, and maybe a "copy from peer" button. I think I can manage that. My question is on how to make what in Dolphin is called a CompositePresenter, which are useful critters. They are not directly tied to a top-level shell, but sending #show to them will create just that, mostly for testing purposes. Is there already something like this in Polymorph? ComposableMorph might be a place to start?? Is there a better way? Bill