Can you screen save on a Nexus 4? I fly a lot, but never accept a mobile boarding pass as I need a decent signal to display it. My iPad allows me to save screenshots to the gallery. I find it incredibly usefull, but can't find it on my Nexus 4!!
If by "screen save" you mean a screenshot, yes you can :)

Just press both Power and Volume Down together and hold them for a second.