Create touchpadbutton

https://help.ubuntu.com/community/SynapticsTouchpad/ShortcutKey

xmodmap -e "keycode 68 = F14"
Then save the config:
xmodmap -pke > .Xmodmap

Openbox. use this:

File: ~/.config/openbox/lubuntu-rc.xml

<keybind key="F14">
  <action name="Execute"><execute>/usr/bin/touchpadtrigger</execute></action>
</keybind>