Changes to captions aren't synced to the editor's gallery view

[ryan]

This was previously fixed in #31329. The bug is back.

See ​https://make.wordpress.org/flow/2015/02/05/caption-changes-are-not-reflected-in-the-editor-macnchrome-4-2-alpha-31332/

To reproduce, add a gallery without captions, click edit, add a caption to a photo, update and nothing changes. Updating the post will refresh the gallery and then the caption is visible.

[dmsnell]

Move rendering into getContent()

[dmsnell]

@iseulde: if you wouldn't mind reviewing this (32779.patch​) I would appreciate it. I'm not sure if overloading getContent() to do an initial render is the idiomatic way, but I came to that when attempting to prevent duplicating the code.

Also, sorry I stole your ticket - I'll look on the assigned-list in the future

[iseulde]

Ideally any change to captions in the media library should update all the gallery views in the editor. They're not stored in the shortcode, so we can't detect a change by looking at that. The best thing to do, I think, is when a gallery view is updated, destroy all instances and render everything again.

[jorbin]

This needs a patch that works as @iseulde outlines. This is a regression so we should get it fixed before release.

[obenland]

@iseulde, do you think you could take a stab at finding a fix here?

[iseulde]

In 33338:

TinyMCE: views: make sure gallery captions update

Part props dmsnell.
Fixes #32779.