MediaWiki 1.28 implemented a new gallery mode called slideshow which does exactly as its name says. The only problem is that the default width can't be changed. If widths="numberpx" is used, it will override the slideshow mode and will display the images as in a regular gallery, but at the specified size. Attempts to change anything in LocalSettings have been futile. Through this task, I would to request, if possible, adjustable widths for galleries in mode="slideshow".
Hey. Could I get an answer if this is something that is going to be worked on (and possibly added) in MediaWiki 1.29? I wouldn't like to insist much on it, but it's something that a lot of wikis (at least mine) would dearly make use of. I would appreciate any answer, even if it's a negative one (at least to know what I should expect for the future).
If you (or anyone) feel like providing a patch to add such functionality, you are very welcome to use developer access to submit the proposed code changes as a Git branch directly into Gerrit which makes it easier to review them. If you don't want to set up Git/Gerrit, you can also use the Gerrit Patch Uploader. Thanks :)