Finally I figured out why my bash commands in the Ubuntu startup application menu weren’t working. For example, I wanted to use this command to set up natural horizontal scrolling in firefox:
sleep 5 && synclient HorizScrollDelta=-68
What I didn’t know for a long time was that this command has to be enclosed in it’s own shell command:
sh -c "sleep 5 && synclient HorizScrollDelta=-68"
Finally I can have the zoom set for my high resolution display, enable horizontal scrolling and set up my graphics tablet automatically after login.