XFCE Split-Wallpaper
Book shelf and stars next to each other
A notebook next to a touch monitor creates an extended desktop. XFCE provides different wallpapers for the monitors.
For many years I have been using XFCE as window manager for my X-server. When adding a touch monitor to my setup I experienced two problems. The easier one is to map the screen to the correct side depending on where the attached laptop stands. The harder one is dealing with touch events on the variable surface of the desktop.
Only the touch screen emits touch events. The area is clearly distinguishable physically and logically. So the touch screen has to become the main screen while the laptop's screen next to it shows playlists, monitoring tools and notifications. Time to adjust the coordinates when touching the touch screen.
One smaller constraint is to not break the configuration when running the latop without the touch screen. This means only built-in single screen setup clearly distinguishable from the touch setup.
Event management is the magic key. When the external touch screen is recognized only its area creates touch events. All coordinates have to be calculated isolated from the builtin screen. A .desktop file manages to issue the commands:
xinput --map-to-output "USBest Technology SiS HID Touch Controller"\
HDMI-0 && notify-send 'Touch-Events' 'Touch-Events auf HDMI-0 abgebildet.'\
--icon=dialog-information
This way xinput routes events from the USBest
device to the coordinates of HDMI-0. Names for the devices can
be queried with xinput list. All output devices can
be queried with xrandr.