SciPhi wrote:So, conceivably can you boot Raspbian to X desktop on touchscreen, then hot-plug HDMI to external monitor and switch to that without reconfigure / reboot?
An applet to effect the switchover would be acceptable : touch it to swap to HDMI and mouse click it to go back... where only "kivy" apps would work on touch while HDMI was primary?
Sorry I don't know if that will work, and I am not using X in any case. The HDMI screen may need the initial Pi handshake in order to set resolution, etc, but I am not sure.
Various male/female 40- and 26-way GPIO header for sale here ( IDEAL FOR YOUR PiZero ):