PS: Hi @pascal, FYI leader has also a bug: When you cancel the text window of the leader command, the leader is still there (leader forgets to update the viewport at the end).
For your purposes a line with Arrowhead should do it, right? and Flip works on that. Here’s a tiny script that you can put on a button with _RunPythonScript
import rhinoscriptsyntax as rs
rs.Command("_Line")
if rs.LastCommandResult()==0:
id = rs.LastCreatedObjects()[0]
rs.CurveArrows(id,1)