Mattermost Server: 5.21.0
Desktop Client: 220.127.116.11682 Mac & Windows
1. Open multiple tabs to the same server
2. In one tab, open a reply thread in one channel and click on the reply box to set focus
3. In the other tab, paste text into the comment field (doesn't matter the channel)
Pasted text only appears in text field with focus (this is how it works in the browser). Subsequent pastes append the text to the other text box. See attached screenshots
The text appears in both text areas when pasted. Cmd+V, Cmd+X, and Cmd+C stop working on Mac.