A common need for Windows 7 touch user interfaces is to react to a touch gesture.  In this screencast, I demonstrate a very simple and easy way to interpret single touch gestures using MouseGestureTrigger from the Expression Blend Samples.

To learn more about Behaviors, Triggers, and Actions mentioned in the screencast, visit http://tinyurl.com/TriggersActionsBehaviors.  If you are interested in touch/multitouch Behaviors, then have a look at http://touch.codeplex.com/.  You can download even more Triggers, Actions, Behaviors, etc. at Expression Gallery.

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Direct link to Ch. 9 post:

http://channel9.msdn.com/posts/keydet/Implementing-Single-Touch-Gestures-with-MouseGestureTrigger/ 

Sample download:

http://tinyurl.com/TestMouseGestureTrigger