
Key events involved in a keyboard shortcut are not completely consumed by Mutter. That means that if the popupMenu is bound to a shortcut (e.g. Alt<Space>) and the user keeps the keys pressed, the same key-event will be delivered to the popupMenu. We can workaround this issue filtering out all the events where a a modifier is down (except capslock). Fixes: https://gitlab.gnome.org/GNOME/gnome-shell/issues/372