Dragging a selection in the source view actually moves the text around

I noticed that when we select something in the UI, and then dragging it. It's a very edge case, and it also thinks that I'm dragging and dropping a new profile first, so I don't know if it's important to fix. But it could be good to fix if it's easy to do.

To understand the issue better, see the video below:

https://github.com/user-attachments/assets/148ea5fc-b4e5-4624-a196-2e12c4fe5254

┆Issue is synchronized with this [Jira Task](https://mozilla-hub.atlassian.net/browse/FP-952)