I have a system with a single monitor, I would like to test the an xmonad configuration that is designed for multiple monitors. Is there any way to emulate a system with 3 monitors using something like Xephyr to test my configuration?
I found the solution using Xephyr and Xdmx
First create the Xephyr displays
This creates 3 windows 1920x1080, each of these will act as a monitor
Next add the xinerama layer onto these virtual displays
Next create a fresh terminal and start your window manager or application like so
or if you just wanted to test an applications xinerama support instead of