The source is responsible for starting a direct manipulation operation. Startup can be accomplished only with a pointing device, such as a mouse. The operation starts when the application detects that a drag button has been pressed and the pointing device has moved. Dragging continues until terminated, which is usually when the button is released.

Although the direct manipulation protocol lets the application use any button for dragging, it is recommended that the system-defined drag button be used for direct manipulation operations.

The source has the following responsibilities in preparing for the actual drag of the objects across the screen: