Feature request: Split dockable areas

[nixRidge]

Description
Which feature or functionality are you missing in Audacious?

I'd like to split a dockable area, so I can vertically resize it independently of other dockables. That is, if this is at all possible in a Qt application.
Here's an example, where I'd like the cover art and playlists to be in their own dockable area, and vertically resize the spectrum analyzer if it were placed beneath the open playlist, without affecting the cover art and playlist manager size.

What makes it beneficial for users?

This allows users more flexibility to place and scale dockable plugins just the way they like, and use a specific size for one plugin without sacrificing a lot of space on other plugins where it's required.

Additional information

• Do other audio players offer this feature?
  Yes, DeaDBeeF. However, this software uses GTK and was written to support it from scratch, so I understand if it's considered out of scope for Audacious.

• Screenshots
  
  

[jlindgren90]

I have not tried it yet but it looks like https://doc.qt.io/qt-6/qmainwindow.html#setCorner could be used to produce the desired arrangement.