I only noticed this problem today because of another problem I've never seen before today.
I rebooted my system, and the OpenDock window opened when I logged in. That has never happened upon login before. Not even just last week when I had to reboot for a system update.
I just wanted to close it and move on to why I rebooted, but clicking the Window Close button wouldn't do it. So I closed it from the Taskbar.
To test it to see if it was just an anomaly or if it would happened again, I shutdown the app and opened it again manually. And the buttons still would not work. But this time my three Tabbed Docks did not open where they were supposed to be. It's happened before. Separate issue. Already reported.
But now I see that someone else has this problem, and that you must click at the top of the Window buttons. That works.