It will be a handy to have ways to add new actions on the go. This could be triggered by pressing a defined hotkey or drawing a defined gesture.
On triggering, S+ identifies the active application (and checks if it matches with the current list of Apps) and opens a dialog box to add an action and assign a gesture. The action could be added to the recognized app as a new app or matched app or as a global action.
Alternatively, this could be triggered by holding a modifier key and then drawing the gesture to be assigned. In which case, S+ additionally recognizes the gesture (similar to training mode) to be assigned to the action.