Start the drag given the initial Cursor to display, a drag Image, the offset of the Image, 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
dragImage		The source's dragImage
imageOffset		The dragImage's offset
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.