ArgumentException: control 1's position in group with only 1 control

I’m getting an ArgumentException:

ArgumentException: Getting control 1's position in a group with only 1 controls when doing mouseDrag

This happens with GUILayout elements when dragging the mouse. What does it mean and how can we solve this issue?

You can find the answer of your questions here :


This explain the reason and solve my problem too so enjoy ;=)