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.