Fix download panel state bug in MediaViewer
completed by: m4tx
mentors: Gergő Tisza
MediaViewer displays images with associated metadata on top of wiki pages. It has a download dialog, which should come up when someone right-clicks on the image; that works somewhat erratically, your task is to fix it (make sure that the flag storing the open state of the dialog is kept up-to-date). You can find the specifics in T86389 in Wikimedia's issue tracker.
Students are required to read Wikimedia's general instructions first.