Steps to reproduce:
- Start VisualEditor.
- Add or edit a simple Maps (Kartographer) <mapframe> element.
- Go to the options tab.
- Click the ••• button next to the language code input. A popup (within the maps popup) to select a language opens.
- Now the entire screen is blocked.
It appears like this is the same issue as in T313690: Dialog buttons not working after required template param warning (due to 'inert' attribute not being cleared). I can find a whole bunch of inert attributes in the HTML. When I manually remove them all it works again.
I wonder how many other places in the hundreds of codebases we maintain have the same problem? Should we revert the patch that added these inert just to be sure? Marking this as a OOUI problem because of this.