The image lightbox feature has display problems in multiple bundled themes

[poena]

The image lightbox displays incorrectly in some classic bundled themes.
It seems the lightbox button is inheriting the theme's button style.

I recommend continued testing in all classic bundled themes.

Testing instructions

Install WordPress trunk (At the time of writing this, that would be the 6.4 beta 1)
Activate a classic theme.
Create a new post or page and add an image block. Select an image.
In the block settings sidebar, enable the option "Expand on Click".

• Confirm that the image shows, both in the content and when the lightbox is opened.
• Confirm that the close button is visible and the button text readable.

Twenty Twenty-One

Image blocks with the lightbox featured enabled show as a dark grey area.
The image only shows when you hover over it.

Twenty Twenty

No issues found

Twenty Nineteen

The image shows by default, but is black when you hover over it.
Opinion: when the lightbox is opened, the close button is not broken but may need some styling to match the theme.

Twenty Seventeen

The image shows by default, but is grey when you hover over it.
Opinion: when the lightbox is opened, the close button is not broken but may need some styling to match the theme.

Twenty Sixteen

The image shows by default, but is blue when you hover over it.
When the lightbox is opened, there is a color contrast issue because the text (the X symbol) in the button is too dark against the blue background.

Twenty Twelve

The image shows by default, but is white when you hover over it.

[poena]

After posting the ticket I found that this was already reported by @wildworks in the Gutenberg GitHub repository ​54940
Let's hold off working on this until we are sure where it should be fixed.

[nicolefurlan]

Sounds good @poena – do we think this will still get completed in the 6.4 release cycle? I'm wondering if we should move it to Future Release.

[poena]

To my knowledge the lightbox feature is still "blessed" by the 6.4 release leads. And including it in 6.4 while being broken for classic themes seems like a very bad idea, to me. So I expect it to get fixed, or the whole feature to be postponed.

[oglekler]

This looks like it should be addressed on the Gutenberg side, so, I am marking this as gutenberg-merge.

[oglekler]

It looks like the issue was fixed upstream, so, after the discussion in the Core channel, I am closing this ticket.

[hellofromTonya]

The fix was included in today's npm package updates, which will ship in RC1.