title: Add dependency property to control
body: <p>I am using the Infragistics XamDateTimeEditor control and I want to add a dependency property to it to allow the developer to choose to have all the text selected when the control gets focus.  I have created a style that is used to set the behavior I want but I want the developer to decide if the behavior should be executed based on a boolean dependency property.  I am not sure how that is done. </p>