Lots of people seem to be asking for this and a lot of the examples are iffy, I thought I'd show you guys how I've always done it. I've commented the events to try to make it nice and easy to understand how it works.
- The method of detecting the speed of the drag and then decelerating can be reverse-engineered into dragging the screen with a bit of work.
- You can very easily add gravity to this by always adding to Y Speed when the object isn't being dragged.
- The object can be made to 'bounce' from the sides of the screen by reversing it's X Speed and Y Speed (multiply it by -1).
- The counters at the top display the X and Y speed and the 'Always' event in the main frame controls them, everything else is inside of the object's behaviour, so you can use it as a widget.
- Detecting the speed of the drag in this way can have all kinds of applications - for example detecting the force and direction of a slice in Fruit Ninja.