FreeCAD is a pretty feature-complete OSS CAD application that has a few idiosyncrasies:

Re-Docking Palette Windows in GNOME

Type a variation of this in the console:

from PySide import QtGui
Gui.getMainWindow().findChild(QtGui.QDockWidget, 'Combo View').setFloating(False)

And yes, this is still present in 2022, with earlier mentions harking back at least 5 years.