When replying to a message, the "Send a message..." box is not focused

[milkcanworld]

Describe the bug

When you click the reply button on a message, you'd expect that the "Send a message..." box be focused automatically, so it is ready to accept input. However, this is not the case, and the box must manually be focused by the user, requiring further mouse use before beginning message input in the case that the user has an addon that responds to key presses installed (e.g. Vimium)

Reproduction

1. Have an addon installed that responds to keys (e.g. Vimium, which for example will open a new tab upon pressing "t")
2. Click the reply button on a message in a chat room.
3. Attempt to type your message, and your addon will be activated instead if a triggering key is pressed.

Expected behavior

No response

Platform and versions

1. Linux
2. Firefox ESR 149.9.0
3. 1.13.1-dev ab80d33

Additional context

No response