feature request: "Draft" mode for reply and post

Motivation: I (sometime) try/need/want to write in-depth answers, which (often) require to quote multiple part of an article or multiple messages.

Relay for Reddit (and maybe others) had a feature which remembered what you already typed in a reply (draft) which allowed the user to enter reply mode, start typing an answer, exit reply mode, lookup some more information, copy some material, reopen reply mode and continue where he left off without losing the previous input.

Alternative: using another app to type message until it's ready.