Windows Style Builder won't save themes

[jwilco777]

I have Windows 10 build 1803 and I have not been able to use Windows Style Builder to build my themes since built 1703 because every time I modify my theme and try to test it or save it the program crashes or gives me an error message saying the theme cannot be used.

[JMB]

Make sure you've updated your classmaps. Also, if you're porting say a theme from Windows 7 or 8.1 (or some lower build of Win10) to a higher build, there are steps you need to go through. And before you test your theme, save it to Desktop or something first then re-open it to test.