Demo video with key casting:
Approximate steps to reproduce: (it's not consistent, and I'm thinking there is some other step I've missed)
- Enter an HTML textarea (I've confirmed this happens in both the GitHub and GitLab comment components)
- Type some text.
- Copy said text.
- Paste the text in the middle of your existing text.
- Click to the end of a line in the middle of your lines of text.
- Type some letters like "asdf"
- Hit enter several times. Notice that no newlines appear.
- Type some more text like "test". Notice that the newlines you added in step 7 now all show up at once behind your previous cursor location.