The scheme selection menu does not offer any hint for the current system
scheme. This also makes it hard to "reset" back to the system scheme, once
the scheme has been changed.
Since, this breaks applications using the action name to save the selected
scheme, I've made a new function in which the action data has been changed from
only the path to the model index, this makes it possible to use the data to
differentiate if the selection action is the system scheme action or not.