Map widget error with touchscreen

I am implementing a map into a tkinter project on a touchscreen device. While moving the map I get an exception in Tkinter callback. "mouse_move_x = self.last_mouse_down_position[0] - event.x
TypeError: 'NoneType' object is not subscriptable"

I believe that this has to do with the touchscreen interaction having no mouse button pressed down. I have tried to resolve this by re-writing parts of the map_widget file but with no luck.

EDIT: I think this is due to my touchscreen interpreting touch motion as a series of mouse clicks. It is the raspberry pi touch and I am stuck on how to fix this

Start in the map_widget file mentioned in the report and reproduce map movement on a Raspberry Pi touchscreen. Trace the Tkinter callback around the reported mouse_move_x line and compare touchscreen motion events with mouse-button events. Done means moving the map by touch no longer raises the reported NoneType exception.