I had a user point this out. If you type ctrl-k (the MS Office shortcut for hyperlinks) you get this panel, which is not the same as the panel you get when you click on the Insert Link button on the RTE button bar.
This is a bug, right? Shouldn't ctrl-k go to the same Insert Link function as the GUI?
The insert/edit link panel caused an issue with the user who wasn't able to use mailto/email links properly, compared to the elegant way the regular Insert Link panel works.