[menu] allow buttons to open menu(list) popups

[scottaohara]

the common expectation on how to build single instances of menu popups in UI is to invoke them from button elements.

<button aria-haspopup=menu aria-expanded=...>
  foo
</button>
<el-menu role=menu>
  <!-- menuitems here -->
</el-menu>

in the menu proposal this use case should be covered - and this could be supported by the command/commandfor attributes, as one idea.

originally, button type=menu was how this had been previously spec'd back when menu was attempting to be something more than another way to spell ul.

[lukewarlow]

+1 for <button command="bruce" commandfor="menu"><menulist id="menu">... that handles the aria for you.

[scottaohara]

add some examples to indicate when people might use this - and provide some examples of when someone might use these vs a menubar to open a menulist

[css-meeting-bot]

The Open UI Community Group just discussed [menu] allow buttons to open menu(list) popups, and agreed to the following:

• RESOLVED: Support opening menulists via buttons with a new command value.

The full IRC log of that discussion

<hdv> scott: commonly if someone wants to invoke a menu or menu list, like 'dot dot dot'/kebab buttons that open a context menus, those are `button` elements
<hdv> scott: in the google doc there was an example of a menu item that opens a submenu. More common practice is to use a button element, would like us to cover that in the explainer
<hdv> +1
<lwarlow> q+
<masonf> +1
<gregwhitworth> q?
<lwarlow> +1
<gregwhitworth> ack lwarlow
<hdv> lwarlow: +1
<masonf> q+
<keithamus> q+
<lwarlow> Proposed Resolution: Support opening menulists via buttons with a new command value.
<hdv> dom9: probably got lost between doc and explainer, we'll try and make sure it gets reflected in the explainer
<gregwhitworth> ack masonf
<hdv> scott: wouldb e happy to propose
<gregwhitworth> ack keithamus
<hdv> s/wouldb e/would be
<masonf> q+
<hdv> keithamus: if I had a kebab menu it would be a button[commandfor], if I want to add one more button next to the kebab menu, I need to change the element and then add a wrapper. Is there a way we can make it such that 1 or n would be the same pattern?
<hdv> dom9: what's a kebab menu?
<hdv> keithamus: three dots
<lwarlow> q+
<hdv> scott: so someone has a single button, and wants to add a second button, they think it would now need to be a menubar
<hdv> keithamus: I could envision an example of a design system where you have a kebab button in the system and when you copy it from the design system… you'd need to refactor a lot
<hdv> scott: fair question… it's a bit of a grey area of… what does the author intend, eg what do they want this to be exposed as?
<hdv> scott: in our design system, we have examples like, if you create some global controls they probably go to a menu bar, if you have one offs, they could be menu bar, or toolbars… what you're talking about now, is probably two buttons next to each other
<hdv> keithamus: so first menu button could be either a menu bar or just a singular button
<masonf> q-
<hdv> scott: they are typically differently styled
<hdv> scott: menu bars often look grouped, by having a visual grouping container… and yeah of course there are cases where designers make 2 singular adjacent buttons look exactly the same as a menubar with two items… but then, congrats, you've made a confusing design
<gregwhitworth> q?
<gregwhitworth> ack lwarlow
<hdv> dom9: it sounds like this is not an accessibility concern. Maybe we could add a little note to explainer to explain difference between singular buttons vs items in a menubar
<hdv> lwarlow: with toolbar if there's less than x items, we could say it's not really a toolbar… maybe there's something like that with menus too?
<hdv> q+
<gregwhitworth> ack hdv
<gregwhitworth> hdv: I think it's a difference in intent with lists
<gregwhitworth> hdv: you can have a list with 1 item which is weird but it's still viable
<masonf> q+
<gregwhitworth> hdv: you can have multiple things that make sense here
<gregwhitworth> ack masonf
<hdv> s/intent with lists/in what the author intents and what the semantics it results in
<lwarlow> Proposed Resolution: Support opening menulists via buttons with a new command value. Add examples to explainer to differentiate between menubar with item menuitem and a single button.
<keithamus> q+
<masonf> +1
<dom9> +1
<gregwhitworth> ack keithamus
<lwarlow> Proposed Resolution: Support opening menulists via buttons with a new command value. Add examples to explainer to differentiate between menubar with single menuitem and a standalone button.
<hdv> keithamus: to clarify, does that mean you can put a button inside of a menu or is that disallowed?
<keithamus> +1
<masonf> +1 still
<hdv> scott: disallowed. This proposal was for opening a menu list outside of a menubar
<hdv> +1
<lwarlow> +1
<hdv> scott: I meant it a little differently from the resolution, but would be fine to add examples
<hdv> lwarlow: I can drop the examples
<masonf> +1 still still
<lwarlow> +2
<dom9> +1 still
<hdv> gregwhitworth: examples seem fine
<lwarlow> RESOLVED: Support opening menulists via buttons with a new command value.