Thanks Garrett,
Here is what I've found:
- Did what you did, built an exe with a VFP base class form - themes works.
- Added a form based on our class called from the first form - themes works!
- Run mis app - themes doesn't work, i.e. toggling the check box the form is always on classical style, no themes.
- added a _screen.themes = .t. to the existing code before the thisform.themes = .t. Now it DOES work!

So, I see two issues:
1. Something in our mis applications startup turns the _screen.themes to .F. Code reference did not find any explicit _screen.themes. Do you know what might set _screen.themes to .F. other than the code assignment?
2. From the help file I did not understand that _screen.themes setting overwrites everythig below. The way it is, you can only have themes as default for everything, and classical style for specified objects, but not classical as default and themes for specified objects. I think I'd like it both ways.

>Beats me -- I created a form with that checkbox and a button, put that code in the InteractiveChange event, built it into an EXE, and ran it from Start-Run: the Themes property toggled properly, as shown on the CommandButton. What are you seeing that's different?