This recipe will work with the last type of events, which is the property event. To be very specific, we will create an invisible widget that will fire an event when a selected property is changed. Just to identify of this invisible widget, we surround it with two normal buttons; thus, the section between them is our invisible widget.
The properties in Kivy have been reviewed in Chapter 1, Kivy and the Kv language, specifically with in the Declaring properties within a class recipe. Thus, it will be useful to refer to this recipe and also to the section on multitouching from Chapter 2, Input, Motion, and Touch.
The recipe is:
ListPropertyfrom Kivy properties.