Properly handle "really wide" blocks when the theme doesn't support them

[withinboredom]

Version: 1.0

Issue Overview

Per #2594, there's not supposed to be a "really wide" button if the theme doesn't support it, however if a post is opened (like the demo) and it isn't supported by the theme, it still shows "really wide".

It would probably be a good idea to do one of three things:

A. Remove the "really wide" attributes from the blocks, when it isn't supported
B. Allow setting "really wide" block attributes even though the theme doesn't support it
C. Do what is currently being done and keep what's there, but don't allow the user to fully express themselves (because the theme doesn't support it).

Choosing choice (A) allows for the possibility of many posts being changed by not choosing a theme wisely and/or noticing that fact for some time after changing to a new theme. Personally, I think this is the worst solution from a UX point of view.

Choosing choice (B) allows for a user to create the post how they see fit, and later find a theme (or wait for theirs to be updated) that allows the best expression of the post.

Choosing choice (C) allows for content to not be modified, except "downward". The user cannot take advantage of fully expressing themselves, except by finding a compatible theme first. This also prevents users from discovering that they may be lacking a compatible theme and just think that the editor is fundamentally broken (as I did in #2594).

I'd personally like to see some kind of hybrid between B & C, where the user can design the post how they see fit, but understand that it may not look "exactly" right until their theme is updated (or they find a new theme).

[karmatosed]

I like the idea unless the theme supports it, it's not shown. But I am not sure of the complications of this code wise. @mtias have you any insights?

[nylen]

As noted at #3516, I noticed this issue because the demo content shows a full-width image, but I can't choose this option in the UI because my theme doesn't support it.

This seems fine, but I don't think the demo content should show features that are not available in my theme.

Here is another possible solution:

Break out the CSS specific to the 'wide-images' => true option into a separate file, and only load this stylesheet in the editor and the frontend if theme support is present.

[wisconsingutenberg]

Is there somewhere we can find a list of themes that support Gutenberg?

[karmatosed]

@wisconsingutenberg right now there is no list but it would be a great community project.

[karmatosed]

As we now handle wide images differently (not showing unless support), lets close this. We can always reopen if needed.

[designsimply]

Is there somewhere we can find a list of themes that support Gutenberg?

@wisconsingutenberg I ❤️ you for asking about this. 😁 I needed one today for testing and here's what I found:

All themes support Gutenberg! Different themes may or may not have support for specific features though (such as wide blocks in this case). Here are a few themes with good feature support for testing Gutenberg that I've been using in using recently:

• Gutenberg Starter Theme
• Navi
• Atomic Blocks