Yes, I know, but that should be the way to dock if you intend it to, not the default in my opinion. Most times I, and I would think a lot of others, just want to move the PRV (or whatever) to a slightly different place and then, 'pop' the darn thing gets docked. There are many similar behaviour options in Prefs (eg what do you want when dragging a clip) and I think this should be one.