e1e878dc76
* Move the chrome panel buttons into a `box` which is inserted into #navigator-toolbox * Adjust what open/closed means using hidden instead * Capture a weak ref to the focused element on open, and attempt to put focus back on exit * Add some restore-focus tests * Fix a bug where cancel via overlay "X" button wasn't exiting properly * Place initial focus in the preview dialog button on the download button Differential Revision: https://phabricator.services.mozilla.com/D181184