I know that I can lock the screen of my Edge 830 by pushing the power button while riding. I usually lock the screen when riding in the rain. Seems like a good idea, but the screen then isn't truly locked -- I can still change the views by swiping. Whenever I try to wipe the raindrops off the screen with my palm, it changes the view or brings up the pull-down menu. What is the point of this? I don't know if this is a feature or a bug.
When I lock the screen, I want to be locked, so whatever touches the screen (my hand included) doesn't affect it.