I saw your request a while back on UserVoice and gave it a go but decided not to look into it too much as it was becoming complicated than I'd hoped. In theory it should be easy since the winforms DataGridView comes with the sorting functionality built in. However our popup can't take focus away from the main editor window and clicking to sort gave focus to the grid, which resulted in our popup closing.
I just gave it another go and I think I've found a simple work around, if all goes well I'll include it in a beta build this week. I'll let you know when the build is up.