Another handy tool I wrote to ease my duties as teacher and lecturer. monitorDaemon automatically remembers display (monitor) positions based on the EDID of the display (only).
Start monitorDaemon, by default it sits in your system tray and does nothing. You need to click the symbol and enable “AutoSave” as well as “Load on Startup” to make use of it. Now it automatically remembers monitor settings that you configure and restores the settings whenever you connect/disconnect a display.
There is a configuration file saved as $HOME/.config/monitorDaemon.ini. It is human readable and all the monitor positions are stored there.
Since monitorDaemon is written in Python, you need Python 2 (!), PyQt4 as well as python-xlib installed. monitorDaemon makes use of the xrandr library via xlib's python interface, not by calling any helper programs.
Get the code at https://www.aboehler.at/hg/monitorDaemon