SC IDE split document navigation (action missing?)

I’ve looked through the Preferences (Shortcuts) and I see actions to work with split documents in the editor (e.g. Split To Right/Bottom, Remove Current/All Split(s), etc.), so I can map key commands to these if desired. Also, I can navigate between documents using Next/Prev/Switch Document (Alt+left/right arrow and Ctrl-tab). But I don’t see any command to switch the document focus between “splits”, so you can move between panes without resorting to the mouse.

Am I missing something?