Pressing backspace in empty message moves you to the edit of last sent
Often you send a "messge"... and oups, you made a small typo. Now you want to correct. Either you do the quick fix and send "*message", or you have to use your mouse to get to the edit mode.
I propose you are moved to this edit mode by repeatedly pressing backspace in an empty message. That is an intuitive way to quickly correct mistakes. Maybe only allow it in the next minute, to prevent accidental backspace deletion.
Shift + backspace would also be an option.