QuickSwitch plugin for UnityEditor
QuickSwitch allows you to minimize any EditorWindow to the floating panel
Use [Alt+PageDown] to minimize
Or use [Window/QuickSwitch/Settings] to set up auto-minimization behaviour
To restore window click or focus its minimized tab ([Ctrl+Tab])
Beware that window settings resets after minimization. I couldn't find a way of saving their settings prior to minimization.
Windows could be truly minimized and hidden offscreen but it breaks ctrl-tab switching and creates redundant windows after restart.