===Requirements:
[] Make it so that a top-level part in the sidebar can be selected (with space, same as parameters). Make sure the selection sticks. The user can tab down to the toolbar and execute functions on the selected part, e.g. move it down multiple steps. (Covered already in T285323?)
[] Let the user trigger all functions via keyboard shortcuts directly in the sidebar, without the need to use the toolbar buttons.
* Ctrl + Shift + {key up}/{key down} to move a part in a multi-part template up/down. (Tools like e.g. PHPStorm use this shortcut for exactly the same function.)
* {key Del} deletes a part.
* Ctrl + {key +} adds a template (allow to do if single or multi-part). If adding a template creates a multipart template, then make the toolbar visible after the user presses the shortcut.
* Ctrl + {key W} adds a wikitext part.
[] Allow power users to also access undoc param input with shortcut key
* Ctrl + __ open undoc param input
This task is split from {T285323}.
===Open questions
* How can a user learn these shortcuts? Consider integrating into {T289653}