Currently using the diamond symbol like the history meta key: https://en.wikipedia.org/wiki/Meta_key
However, this key is actually interpreted as the Super/Windows key but
Android calls it "meta" internally.
It is placed on the top-right of the enter key on every layouts.
It sends a special event (performEditorAction) instead of writing a
newline.
The "actionId" is passed through the EditorInfo object in an obfuscated
way so it's not clear whether it's using the right one.
