MultimediaViewer is a MediaWiki extension that gives the user of a wiki a slightly nicer interface for viewing full-size, or nearly full-size, images in their browser without extraneous page loads or confusing interstitial pages. It is currently a beta feature deployed in all Wikimedia sites.

Currently it has this little problem:

The 'use this file' dialog doesn't prevent clicks from going through to
underlying UI, including the link that pops up the dialog in the first place --
you can actually pop up multiple copies.

See this bug report for more information:
https://bugzilla.wikimedia.org/show_bug.cgi?id=56501

Please ask any questions in the bug report. You will have better chances for quicker and better answers from the project maintainers and other community contributors.

Students are required to read Wikimedia's general instructions first. Patches should be submitted to Gerrit and reference the bug report in the commit message. Improvements to an initial patch must be submitted as an amendment  to the initial patch, not as new patches.