@danyhkim said:
By pressing the shift key while dragging, an object may be dragged in the 'upward' direction. Releasing the shift key restores horizontal dragging while the object is suspended above the ground.
Ha Ha. Doing this reminds me of the animated version of "Flatland", in which one character tries to tell the others about "up". The others just say "You mean 'north', don't you?"
thank you for the solution