"File upload" Window hidden behind whiteboard with Internet Explorer 11

This bug doesn't occur in other browsers (tested in Google Chrome or Mozilla Firefox), but in Internet Explorer 11 if you try to upload a file on the whiteboard (Files - File upload), the "Choose a file" window only appears behind the whiteboard. If you resize the whiteboard before clicking on "File Upload" you can actually see the window and move it/use it, but if you let the whiteboard at its default full size (when you enter the room), the "Choose a file" window will be completely behind the whiteboard, unclickable, unusable, nothing else will be clickable and you get stuck there. You can either refresh the whole page and get back in the room or completely restart Internet Explorer.