touchpad: add a setting for enabling it when no mouse is connected
At the moment (4.18) the user can activate/deactivate individually the mouse and the touchpad. I can use both the mouse and the touchpad, or one of them, or none.
My proposal is: Add a control to the touchpad settings, that activate automatically the touchpad when no mouse is connected.
My use case:
With my laptop, I normally use an usb mouse, and I keep the touchpad disabled, because when I inadvertently touch it, the mouse cursor goes where it wants!
Sometimes, however, I cannot use the mouse, and I must then enable the touchpad, and disable it when I go back to using the mouse. It's very annoying!