Yep annoying. I have a few workspace profiles saved for this very reason. If I'm specifically working on one file I have a main screen and the floaty bits/windows. I'll often also use Windows multiple desktops to give me ++space in this instance.
Multi-file projects I use a more compact more 'docked' workspace so I can drag it to one or the other monitor but the find box for example tends to remember where it was last opened. Annoying but manageable.
Definitely it should pop to the front and maybe set off a flare to let you know that it's hiding in plain sight just not where you expect it.
Also this would be a great one for BIM manager's working on a random pc not set to your own OCD arrangement.
Hope this helps.