Think of when this happened to you (because i know it has):you've go the camera right where you need it, you got the part pulled from the menu, and there is a tiiiiiiny hoke where you've got to put it to make your plane perfect. You drag it into the hole, but suddenly, it zips off your finger and next to the hole. So you slightly move it back in. It sits where you want it. You move your finger off the touch screen, and suddenly, its out of plane again. After rinsing and repeating for 10 mins, it finnaly stays. Lock butten stops it from happening. When you get the part in place, hold the button with your other finger and the part wont move, making it safe to take you finger holding the part off the screen.

@DarkLithium Just hold down on it.

@amazingperson124 I can't figure it out, how do you use it?

Sometimes a part is in a position where it rapidly alternates in between two positions. The lock button stops it from moving and saves hours of frustration.

I don't use it