This won't work on a lot of browsers, but temporarily just target modern ones. (Robust solution is possible using classNames and refs)

Thanks @towerofnix!

Including action-menu which was also giving one when the backdrop library opened.
Localize the costume library, I missed it while doing the other libraries.

Thanks @ericrosenbaum!

Fix issue with sound upload button not always working, and correctly cache sound type if given an mp3.

There's a subtle difference in behavior between mouseup and click. Using mouseup allows you to close the menu by clicking its opener item.

whoops