Button: Add support for :hover in variation theme.json

[richtabor]

I expected to be able to manipulate the hover state of variations from theme.json. I can define the other default state attributes, but hover is not supported. Ran into this while exploring adding more variety to the buttons in TT4 theme variations: WordPress/twentytwentyfour#646

Related to #49716.

[masteradhoc]

+1 in getting this into theme.json and also in Global Styles

[pablost88]

I had the same issue a few days ago. My workaround was to add some css to the core/buttons block using the "css" attribute. Hope it helps

[philhoyt]

+1 hover states in theme.json and global styles would be welcomed!

[Zealth57]

Also related #51337 and #64362 and discussed in #core dev chat today. Seems to becoming a consensus that at minimum we should expose some APIs to allow developers to implement better controls in the Elements. This would allow the flexibility to create states or create more flexible elements as needed.

[joemcgill]

The related PR: #67541 makes some initial progress on this.

[carolinan]

This is unrelated to the stylebook, and it is unrelated to the type of elements available.

Elements and variations can both be used under styles and under styles > blocks > block name.
But elements can not be used under variations.

But the following is also problematic because the button element is not part of the button block.
Even if this was possible, it wouldn't apply any styles:
core/button > variations > slug > elements > button > hover

And with this, it would be unclear what to apply the hover on:
any other complex block > variations > slug > hover
any other complex block > variations > slug > elements > hover