Invalid region(s) detected - Highlight the region

[skywalkerisnull]

When you accidentally (or on purpose) don't tag a region we get this pop-up message:

A few improvements to the message and functionality:

1. Number of regions that are un-tagged. The message current says 1 or more.
2. Allow us to highlight (flash, fade, change transparency, edge thickness changes etc.) the region(s) that are not tagged.
3. Allow us to assign all un-tagged region(s) to a specific tag.
4. Allow us to discard the un-tagged region(s).

Something like this:

[marireeves]

This would help.