We show how to design touchscreen widgets that respond to a finger's contact area. In standard touchscreen systems a finger often appears to touch several screen objects, but the system responds as though only a single pixel is touched. In contact area interaction all objects under the finger respond to the touch. Users activate control widgets by sliding a movable element, as though flipping a switch. These Sliding Widgets resolve selection ambiguity and provide designers with a rich vocabulary of self-disclosing interaction mechanism. We showcase the design of several types of Sliding Widgets, and report study results showing that the simplest of these widgets, the Sliding Button, performs on-par with mediumsized pushbuttons and offers greater accuracy for small-sized buttons.