Add slideUP/slideDown transitions to the menus accordion

[DrewAPicture]

We talked about this early in the cycle in #23119 and other places, but it would be nice to not make switching between accordion sections so jarring.

A slideUP/slideDown transition similar to how we're handling post formats in #19570 would be a nice UX addition.

[markjaquith]

In 23856:

Use jQuery.on() properly in accordion code. Some other cleanup.

see #23890.

[markjaquith]

Doing some other cleanups here while I'm in it.

[markjaquith]

In 23858:

Simplify the accordion sibling-section-closing JS.

see #23890

[pragunbhutani]

There's this one solution I'm uploading, but I'm not sure it's a good one.

Basically, the slide toggle was acting jumpy because of margin and border values. Similar to this ​problem.

I've added .slide-helper and .margin0 classes as a workaround because I didn't want to mess with existing classes for the fear of breaking something.

[kovshenin]

23890.2.diff​ adds sliding to accordion.js. This should cover both the menus UI as well as the customizer.

[pragunbhutani]

It seems I've added my patch based on the code of version 3.5.1!
I realized this when I was trying to apply kovshevin's 23890.2.diff and couldn't find accordion.js

What becomes of my patch now?

[DrewAPicture]

23890.2.diff​ works well for me, see here: ​http://screencast.com/t/vNbyJnQh1KYW

[nacin]

The screencast indicates the animation here is way too slow. Needs to be snappier. But larger point: Is this necessary?

[DrewAPicture]

fast

[DrewAPicture]

Replying to nacin:

The screencast indicates the animation here is way too slow. Needs to be snappier. But larger point: Is this necessary?

Seems to me this would add just a teensy bit of polish and remove the jarring switch from box to box. A quick audit of other slideUp/slideDown usage in core shows 'fast' as the standard speed.

23890.3.diff​ adjusted to fast: ​http://screencast.com/t/GWIDrOkO

Without animation: ​http://screencast.com/t/0J5vrL2SPQt

[helen]

I find it much easier to reorient myself with the animation. Definitely fast, though.

[helen]

In 24644:

Add sliding animations to the accordion. props kovshenin, DrewAPicture, helen. fixes #23890.

[celloexpressions]

#13147 was marked as a duplicate.

[DrewAPicture]

#13147 was marked as a duplicate.