ThemeServices has an OnThemeChange callback for this already. Adding it
to TApplicationProperties wouldn't be a terrible idea, though it would
probably be better to implement CM_THEMECHANGED/CM_STYLECHANGED in
TControl, which would be VCL compatible. I haven't tested it on most
widgetsets, but
This forum topic is about how we can react to macOS theme change.
https://forum.lazarus.freepascal.org/index.php?topic=43111.msg376056;topicseen#new
and I had the idea to make all this task simpler.
we have the TApplicationProperties. let's add OnThemeChange there!
some widgetset funcs will be ne
