Implement dragging behavior.
Adds drag behavior to popup.
Dispatch touch to children when outside dragging box.
Don't skip if touch collided.
Don't add drag behavior to popup.
Add example for making popup draggable.
Call super when not handling touch.
Ungrab touch only if it's our touch.
Merge branch 'add_drag_behavior' of https://github.com/matham/kivy into matham-add_drag_behavior
dragbehavior: move back the configuration token to the top
Merge branch 'master' of ssh://github.com/kivy/kivy