@Norman P do other apps pick up the chnaged appearance properly ?
In the event you can do anything. Consult any property and statuses and adjust whatever you need.
But... In the above Dark mode losing the context, as the "Dark mode" is something Xojo implemented by itself, they need to intercept such conditions and context aberrations as reported (if I understood correctly, the dark mode changed in the "suspend event" and the GUI returned crazy after resume), and handle them (like fire a timer event to an internal ReadjustThingsInCaseOfDarkModeChange()), BEFORE bubling up the resume event to the user. In such case, the "dark mode" inconsistencies should work without the user intervention.