Thanks for reaching out to us with your question!
Unfortunately, there isn't any built-in option for dragging plot lines and it would require extending its' functionality with dragging possibilities. Perhaps you might be interested in a solution based on this topic: viewtopic.php?f=12&t=50424
. This approach requires adding a line annotation with control point disabled and dragging enabled only for x-axis.
Let me know if that was what you were looking for!