Meter Control Window

Hello, When I activate some meters during record or playback they are displayed as part of the audio files workspace. However, when I activate the phase meter it opens into a separate control window. Can someone tell me how to prevent the phase meter from opening into a separate control window? Thanks.

Just dock it to the window you like.

I have read the manual re. docking and undocking. I have dragged the control window with the phase meter around, double clicked it, etc. but nothing I do causes the meter to become part of the audio file workspace like other meters. What am I missing?

If you can see this space, click in the middle: