Input validation

[verhovsky]

When I type a keyboard shortcut like "command+j" I don't know (without reading the docs) how I'm supposed to write it, "cmd", "Cmd", "command", "Command", "⌘", whether I can include spaces between the "+", whether I'm allowed to add more keys with "+".

It would help if you added a simple green checkmark when the text I type can be parsed and/or a red box around the output when the text I entered doesn't match a known key, preferably with a specific error message on what went wrong.