Starts the drag given the initial Cursor to display, the Transferable object, and the DragSourceListener to use.

Parameters:

dragCursor		The initial Cursor for this drag operation or null for the default cursor handling; see DragSourceContext for more details on the cursor handling mechanism during drag and drop
transferable		The source's Transferable
dsl		The source's DragSourceListener

Exceptions:

InvalidDnDOperationException

if the Drag and Drop system is unable to initiate a drag operation, or if the user attempts to start a drag while an existing drag operation is still executing.