Panel width for plugins do not persist

[BeatLink]

Environment

Joplin version: 2.4.12
Platform: Linux
OS specifics: Linux Mint Cinnamon 20.2 (Flatpak install)

Steps to reproduce

1. Install a plugin that utilizes the Panel API (such as Outline or Agenda)
2. Toggle the panel visibility via the plugin (Hide the panel then show it)
3. Note that the panel does not remember its original size but instead expands to the initial width (half of the editor usually)
4. Note also that there are no API functions to either retrieve or set the panel width, hence this issue needing to be solved upstream.

Describe what you expected to happen

Either joplin should expose an API for managing the panel's width or height (getting and setting) so developers can manage width/height themselves, or the core joplin code should automatically remember and restore the panel width/height

Logfile

[msbentley]

Linked to this issue I guess: cqroot/joplin-outline#33 and a high source of frustration for users of this and similar plugins ;-)

[micmalti]

This bug didn't bother me until I switched to v3. Now, every time I switch to a note without an outline and then back to another one that does, the panel widths reset. I'll be staying on v2 until this issue is resolved.