Dragging and dropping staging part icons

[jon_joy_1999]

KSP V0.90.0.705 Windows 64-bit

What happens: moving staging icons for parts interacts with actual parts behind the icons

Mods: Navhud 1.1.3, MechJeb2-2.4.1.0

Steps to replicate:

1. create a large(wide) craft, or zoom close to a narrow craft so the staging line is covering a portion of the craft
   
2. drag a part staging icon on the staging line to a portion of the stage that covers the craft and drop it
   

Result: the portion of the craft that the mouse was over while dropping the part staging icon is now selected and being dragged by the mouse despite the mouse not positively clicking on the part