If i set up my keys in Ubuntu as Alt+Shift for change input method, it is conflict with "Hud" in Firefox wich try "open" menu. Its very annoining behavior, and i cant normally type on 2 languages.
i've already install add-on from Mozzila help link ( https://support.mozilla.org/en-US/kb/keyboard-shortcuts-perform-firefox-tasks-quickly ) , that can customize shortcuts, but i cant find there only this option with "Alt" all another exist. Also when i change inputs this bug make a new-line in comments on vk.com site so i need delete it ;(((
OS: ubuntu 16.04 server + gnome Firefox 52.0.2 (64-bit)