Being proposed for Q4 via our quarterly grooming process.

Test wiki on Patch demo by ESanders (WMF) using patch(es) linked to this task was deleted:

This works for me — the caption remains centred, but is centred within the gallery instead of within the whole page width.
In mediawiki.page.gallery.styles/gallery.less
Change:

ul.gallery.gallery.gallery {
    margin: 2px;
    padding: 2px;
    display: block;
}

to

ul.gallery.gallery.gallery {
    margin: 2px;
    padding: 2px;
    display: inline-block;
}

The laws of nature being what they are, I suspect that is just too simple to be globally valid.

@Pppery added a project: TestMe.

Change #1070554 merged by jenkins-bot:

[mediawiki/extensions/VisualEditor@master] MWGalleryDialog: Highlight item at closest index when removing an image

https://gerrit.wikimedia.org/r/1070554

Change #1079939 merged by jenkins-bot:

[mediawiki/vendor@master] Bump wikimedia/parsoid to 0.20.0-a25

https://gerrit.wikimedia.org/r/1079939

Change #1079939 had a related patch set uploaded (by Isabelle Hurbain-Palatin; author: Isabelle Hurbain-Palatin):

[mediawiki/vendor@master] Bump wikimedia/parsoid to 0.20.0-a25

https://gerrit.wikimedia.org/r/1079939

Change #1079047 merged by jenkins-bot:

[mediawiki/services/parsoid@master] Allow localized gallery widths

https://gerrit.wikimedia.org/r/1079047

Change #1072822 abandoned by Arlolra:

[mediawiki/services/parsoid@master] WIP: parse gallery specs with localized 'px' suffixes

Reason:

In favour of I38733e08f6cbe10b7ae2e634fc53d7ddd6415599

https://gerrit.wikimedia.org/r/1072822

Change #1079047 had a related patch set uploaded (by Arlolra; author: Arlolra):

[mediawiki/services/parsoid@master] Allow localized gallery widths

https://gerrit.wikimedia.org/r/1079047

In T374311#10186201, @stjn wrote:

Currently this is confusing some editors who think that because there is a tracking category added to <gallery> images because of this bug, they need to remove px from the galleries. What is holding back the patch from getting reviewed?

Change #1072211 merged by jenkins-bot:

[mediawiki/core@master] Allow localized gallery widths; avoid spurious "double px" tracking category

https://gerrit.wikimedia.org/r/1072211

Currently this is confusing some editors who think that because there is a tracking category added to <gallery> images because of this bug, they need to remove px from the galleries. What is holding back the patch from getting reviewed?

The gallery tag has a host of issues particularly with . At this point I would personally recommend it gets rebuilt from the bottom up given the amount of associated issues- but this particular issue is covered by T370093

Change #301129 abandoned by Hashar:

[operations/mediawiki-config@master] Change default gallery mode to 'packed' on the English Wikipedia

https://gerrit.wikimedia.org/r/301129

Change #1072822 had a related patch set uploaded (by C. Scott Ananian; author: C. Scott Ananian):

[mediawiki/services/parsoid@master] WIP: parse gallery specs with localized 'px' suffixes

https://gerrit.wikimedia.org/r/1072822

Change #1072211 had a related patch set uploaded (by C. Scott Ananian; author: C. Scott Ananian):

[mediawiki/core@master] Allow localized gallery widths; avoid spurious "double px" tracking category

https://gerrit.wikimedia.org/r/1072211

The width *should* be parsed with the "magic word" img_width, which includes the trailing px (localized in many cases, for example in Esperanto it also allows a trailing re). As such, the value which arrives at Parser::parseWidthParam() should /not/ have a trailing px.
It appears that renderImageGallery is not parsing the widths attribute with img_width (which also means the attribute value is not being properly localized). I'll work on a patch.

@Pppery I'll take a look. It's not intended, but gallery *is* somehow triggering the code path where "px has already been parsed and we saw another one". Perhaps that's because gallery itself is adding a hidden px.

In T374311#10131678, @Pppery wrote:

@cscott Is this intended to populate the tracking category? I personally think it's reasonable behavior that both <gallery widths=180> (concise) and <gallery widths=180px> (technically redundant but clearer) are accepted and don't populate the category. Both syntaxes are widely used.

This is clearly a bug.

@cscott Is this intended to populate the tracking category? I personally think it's reasonable behavior that both <gallery widths=180> (concise) and <gallery widths=180px> (technically redundant but clearer) are accepted and don't populate the category. Both syntaxes are widely used.