This Button signals that a search is possible by showing a magnifying glass to the right of a search box. In this state the button is not enabled. When a search is active, it changes to an X that is enabled and when clicked on will revert to no search being active. Most of the work happens in the SearchIsActive setter. The Button's click event should be hooked up to a handler that clears the search (text) and (consequently) sets SearchIsActive to false.
