Edit: Oh and once you have a reproducable case you can send me, you can reset your layout from Window>Reset Window Layout.
Hmm this was supposed to be fixed in RC3. Are you sure this wasn't left over from a previous config? Did you delete your config-dir/19.0.0 folder and let it migrate from your 18.0.x folder? I would like to reproduce this, so if you can get it to the state just before it happens, then send me the offending (maybe v18) vrestore.slk that would help.
++rodney