Some keyboard inputs are suppressed in the editor

[rzumer]

On my keyboard layout (Canadian French), the following inputs don't seem to do anything in the editor:

• Alt+key combinations (which I use for brackets and a few other misc. characters)
• Key modifiers (e.g. `, which on my layout can be pressed once prior to a vowel to display a grave-accented character, or twice to display a backtick)