Implementing this would be trivial, because you're using ooui for your buttons and so all you need to do is tell it about an accesskey in the widget config.

You would need to switch from OO.ui.ButtonInputWidget to a plain OO.ui.ButtonWidget` because the former doesn't have AccessKeyedElement mixed in for some reason... but you're not using this in the context of an HTML form, so you don't need to be using ButtonInputWidget anyway.

"Favourite Template (Ctrl-L)" or whatever the hotkey actually is, I haven't found it yet if any exists.

None exists yet.

The main reason we've not added an accesskey is that it's hard to decide what it should be! There's an up-to-date list at https://www.mediawiki.org/wiki/Manual:Access_keys of the currently assigned accesskeys. Suggestions welcome!

So if I hover over the Favourite Templates button in the editor I want to see

I'm assuming this means on the button after selecting a template, as in on the template parameters' page? (And the same could be used on the template pages.) Because it's not possible to have an accesskey on all the favourite buttons in the search results or favourites list.

@Samwilson It would be really cool if I could add an accesskey to a particular button in JS. Do you happen to know how I would achieve that?

So for example, let's say I want Ctrl+L to open the Favourite Templates dialog box.

I'm assuming this means on the button after selecting a template

Here is a screenshot that shows what I mean, I added the "Ctrl-L" bit:

You can't see the mouse cursor for boring technical reasons but imagine that there is one next to the tooltip.

The buttons in the WikiEditor toolbar are OOUI buttons, so you just need to pass in accessKey when creating them. E.g. this patch would automate it: https://gerrit.wikimedia.org/r/c/mediawiki/extensions/WikiEditor/+/1172895

If you wanted to do it after-the-fact because you're doing it in a userscript, it'd actually be a bit of a pain because only some of the buttons are set up as ButtonWidgets, and others are ToggleButtonWidgets which (for some reason) don't have accessKey mixed in -- but e.g. here's how to add one to the reference button: $('.tool[rel=reference]').data('ooui').setAccessKey('d')

Technically you can also just stick an accesskey attribute onto the appropriate element, but it wouldn't give you the effect on the title, and there's some issues with the focus that'd need to be addressed as well...

Actually, see: T400583

There's a difference between accesskeys (browser-based) and the opt- or ctrl- based ones such as ctrl-K to insert a new link. The latter are provided by VE and WikiEditor and can sometimes clash with web browser shortcuts. For example, ctrl-L selects the browser's address bar, and ctrl-M mutes the current tab or in VE removes formatting from the current selection.

Should we use L as the key, then? As far as I can see we don't have a registry of non-accesskey keys. We'd want to have it be the same in VE and WikiEditor.

I think ctrl-E might be a good alternative. It focuses the address bar in Chrome I think, but not in Edge or Firefox (whereas ctrl-L does that for all of them).

On macs cmd+E is "use selection for find" as a standard system-level shortcut. (But on macs we've already got conflicts -- WikiEditor does cmd+, for subscript, which is the absolute system shortcut for "open application settings".)

In T399295#11041550, @DLynch wrote:

On macs cmd+E is "use selection for find" as a standard system-level shortcut. (But on macs we've already got conflicts -- WikiEditor does cmd+, for subscript, which is the absolute system shortcut for "open application settings".)

Yes, Command + [,] so thus in Safari it opens the Settings for the browser, but surprisingly in Chrome when the cursor is placed in the active editing window the shortcut works! (See related T400569 for the same keyboard shortcut conflict in VisualEditor.)

The { accesskey isn't currently used by any extensions or core, as far as I can see. That's sort of similar to ) which is used to reload the realtime preview.