[SOLVED] How to redock an undockable dialogue?

[gnuimpcub]

(03-22-2018, 07:43 PM)rich2005 Wrote: Click in the tool options tab and drag into the "you can drop dockable dialogs here"

screenshot here: https://www.gimp-forum.net/Thread-Can-t-...18#pid3618

There is an option in that little left pointing arrow to lock the dock in place.

Thanks, I knew that, but if I choose "Lock Tab to Dock" nothing happens. The "tool options" floats as before!