I LOVE THIS 
A few (minor) things:
changing images
Yes, that would be better - the current implementation is REALLY confusing to people. And a feature should only be “fun” when it does not decrease clarity.
component list sorting
The filters are handy, but it would be even better if the sort column order was Enabled - Used - Name.
used by
I think this looks a bit messy where the theme name is split over two lines. Maybe the theme names could look like a label as well, with a slightly different background color to visually separate it from “Unused”?
And when I could click on a label and it would automatically filter so I would only see components used by that specific theme then it would be awesome.
But right now, it’s already very close to awesome!