I would love to see the ability to apply all changed properties to all descendants of a window.
I have a particular use-case where every individual window component is disabled and being able to just select the parent and set "Enabled" and unset the "WS_DISABLED" style flag would be incredibly useful.
When I get time I may try to set up a visual studio development environment and have a crack at this however I'm not too skilful in C++.