Good morning TOAD team,
This morning it only happened once in the latest beta, 18.104.22.1686. I closed TOAD with task manager and restart issue gone. Yea, the X to close TOAD also failed.
The one time issue is that the TOAD main window became modal and stayed on top of everything, including the list of users to connect as. I usually keep TOAD maximized so would not notice this unless the new connection dialog was pop-behind, as it was. But even selecting it, it was still behind the main TOAD window.