I did notice trying Julian’s ZOrderFix on one of my program that has transparent ContainerControl in front of other controls, that made them non transparent, yet their zOrder was not changed.
It is pretty obvious by now that ZOrderFix is not the magic pill more than declares that stop redraw, or other expedients. I use much too many canvas and containercontrols to rely on that.
For now on, I will be slowly refactoring my Windows programs to simply do away with conventional controls, in favor of a single canvas UI.