Disable new Slack WYSIWYG editor with this bookmarklet
Just got another note from them:  We really appreciate your feedback, and we hear your frustration. 
  We're sorry for the impact this is having on your ability to communicate with your team and on your overall productivity. 
  We made a mistake by forcing everyone into this feature without providing an opt-out for customers like you: people for whom the existing behavior was working just fine.

  We've started working on a preference that will let you return to the previous message composer. 
  We don't have a specific release date to share right now — it's this team's top and only priority, however, and we expect to have it available on the desktop within a couple of weeks, with Android following shortly thereafter.

  We will follow up with another note when this option is available to you, and we'll include instructions on how to enable it.

  Again, we're sorry for the disruption and we're grateful for the feedback. 
  We missed the mark on this feature! We will do our best to learn from this and avoid similar mistakes in the future.