Slack is similar Shift enter in normal text. Enter in a code block, shift enter sends in a code block.

I just tested this on Slack (macOS) and it's not the case. Pressing Enter in a code block submits the message, just as it does for any message.

The Signal desktop app does both too, I guess, but in a way that actually makes sense. Enter sends a message since IMs tend to be short one-liners. Shift-Enter inserts a line break.

But if you click an arrow on the top of the text box, it expands to more than half of the height of the window, and now Enter does a line break and Shift-Enter sends. Which makes a lot of sense because now you're in "message composer" / "word processor" mode.

I would say it mirrors common behavior in the Web, which in turn was largely influenced by old desktop software: Enter in a `<textarea>` inserts a line break, while enter in an `<input>` submits the surrounding form (or does nothing). It is an established idiom after all, many apps just get it wrong.

I have a very mild jolt of anxiety every time I want to enter a new line in Teams or Slack, wondering if it will send a half completed message I will need to edit after the recipient has seen the half completed message, or it will enter a new line like I want it to.

The behavior also changes if you start editing a numbered or unordered list. Maybe that enters the "formatting tools" mode you mention?

If you're worried about this, consider a copy and paste from notepad.

Note the "very mild" jolt, not quite enough to rise to the level of switching to Notepad (or Emacs in my case).

Your advice beautifully reinforces OP's case. We now have to use auxiliary apps with more predictable behaviour because designers made such a mess of things.

We've still yet to reach the "any textbox is just an embedded version of your EDITOR" nirvana.

Shift enter should always put in a new line. Good luck exiting a block though with it.

Teams is insane. You want a new entry in a bulleted list? Hit the enter key. If you dare.

I had managed to be on Slack exclusively for at least 10 years. Recent acquisition has me using Teams and it's hilarious to see for the first time what people have been complaining about. I thought surely people are exaggerating. No, no they are not.

It only took a couple weeks for me to figure out that I would have to compose longer messages somewhere else and then paste them into Teams.

Teams also respects some standard markdown, like italics, but not others…like bold.

MS is amazing in their ability to fuck shit up for no apparent reason. Like making a media player that doesn’t use space for play pause…

Unfortunately, some markdown renders differently when copied in vs when typed directly in teams.