How can I stop the left alt key opening the application menu on Ubuntu 18.04?

I have Ubuntu 18.04 installed with GNOME.

My left alt key opens application menu while right alt works as expected (left alt + F4 doesn't work for example, right alt + F4 works perfectly).

How can I fix the left alt behavior so that it works like right alt?

1 Answer

The terms we are discussing here are "keyboard shortcuts" and "keybindings". They are useful when searching for help.

First, run xev in a terminal to see if the key works.
If it works, open Settings > Devices > Keyboard for a list of shortcuts. If it says Alt without specifying right or left they should both work. Replace any that specify a side and make sure it only says Alt.

If you have trouble making the settings do that, install dconf-editor

sudo apt install dconf-editor

and launch it from the terminal

dconf-editor 

Locate the search icon and type keybinding and look through the paths for what you need. In your example navigate to

org/gnome/desktop/vm/keybindings/close 

If the default value is on it should be set to

['<Alt>F4'] 

If it's not, switch default to off and enter exactly the above as a custom entry.

My Alt shortcuts seem to be the same for each side, so maybe yours got reconfigured somehow.