I've realized I also use shift + scroll when I end up with a graphic artifact left on the screen after dragging something around on the block diagram. I quickly scroll up or down until the ugly bit is off screen and then back to where I was. After being made aware of it today, I realize I do this a fair bit.
Duplicate of http://forums.ni.com/t5/LabVIEW-Idea-Exchange/Horizontal-Scroll-Hotkey/idc-p/977860