I've just flashed Ubuntu Touch & Android dual-boot onto my Nexus 4. It's awesome with a mobile device running two OSes at the same time.
I want to know that how can I take screenshots on Ubuntu Touch running on Nexus 4?
phablet-screenshot from phablet-tools package. or mirfbdump (a bash script, orginally not support Nexus 5)
perhaps can help you. but to me, all fails. sad..... I use Nexus 5.
Using the devel channel for mako (nexus 4) if you hold down both the volume buttons together it takes a screenshot.