Dear Maintainer,

when Firefox pops up a notification (as in "Allow website X to display
notifications"), the popup window has the wrong X11 window class (at
least I think that this is the problem).

This results in my window manager (xmonad) to display it like other
application windows, not as a popup window, distorting my window
arrangement.  This worked fine prior to the recent upgrade,
i.e. previously the popups were rendered as a popup overlay in a
screen corner, not distorting the window arrangement.  Note that I'm
using X11.