Make sure events with modifier keys are ignored in MediaViewer
completed by: ☃ unicodesnowman
mentors: Gergő Tisza
MediaViewer displays images with associated metadata on top of wiki pages.
It listens to various keyboard and click events. When this events happen with a modifier (e.g. Ctrl-click or middle-click instead of a normal left click, or Alt-right arrow instead of just the right arrow), the user is probably trying to do something other than we expected, and the event should not be intercepted. This is already done for some event handlers, but not consistently. The task is to make sure it is done for every event handler where it makes sense.
This is T68329 in Wikimedia's issue tracker.
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