[switch-views:] If only the editor is visible: The shortcut `editor-↔-sidebar` puts the focus on two places

[ralf3u]

Steps to reproduce

1. Only the editor is visible
2. Press the shortcut switch-views-(editor-↔-sidebar)
3. Click on the tab-title Preview
4. Press twice the shortcut switch-views-(editor-↔-sidebar)

Result
The Preview-tab is visible.
The Preview-tab-title is not in focus.
a) The frame or border of the sidebar is in focus because editor is not visible. Reason: If I press 1x the arrow-left-key, then the content-area of the preview is in focus.
b) Instead of doing a) do this:
The tab of the editor is still in focus, because I can tab-browse with Ctrl+PageUP/PageDown in the editor, although the editor is not visible.

Expectation
The focus should be only on one place.

Possible solution
What about to unfocus the editor when the editor is not visible?

[ralf3u]

The frame or border of the sidebar is in focus [...]

I ask myself what exactly is in focus. The frame, border or something else of the Preview-tab? One thing is clear: It is not the tab-title of the Preview-tab (tab-title of the Preview-tab gets focus with this code: geany.signal("notebook3", "grab-focus"). What exactly is in focus could be seen by creating different colors for the frame, the border and so on. And when something gets the focus, then it changes the color. I seem to remember that you created something like that in the past. Do you know what is in focus?

Important remark
When the editor disappears, the frame, border or something else of the Preview-tab has focus automatically, no matter if sidebar_focus() exists, because sidebar_focus() does not work at all.

[ralf3u]

I ask myself what exactly is in focus.

Yes, because maybe it is the frame that is in focus, and maybe the frame can be set with CSS to 0, so that maybe then the content area will be automatically in focus because no frame exists any more.