Can't re-dock panels on Debian

Hi,

Yesterday I un-docked the live preview panel by mistake. According to the manual I should just drag it at the edge of the window, which should highlight, and then the panel should re-dock. This is not happening, the window remains floating. I tried to un-dock the file browser and now I can't re-dock that either :smack:

My wife has the same problem on her laptop. We are both running Debian on different machines.

Is there a setting I can't find or something like that, or should this be flagged as a bug on github?

Thanks!