nsIDragHelperService Interface

 Call when a drop occurs inside the rectangle bounding the browser.

 @param inDragRef the native DragReference
 @param inSink the event sink to which the event will be dispatched

 @result <code>PR_TRUE</code> if the drag was accepted by Gecko.

boolean drop(in DragReference inDragRef, in nsIEventSink inSink)

 Call when the mouse has entered the rectangle bounding the browser
 during a drag.

 @param inDragRef the native DragReference
 @param inSink the event sink to which the event will be dispatched

void enter(in DragReference inDragRef, in nsIEventSink inSink)

 Call when the mouse has left the rectangle bounding the browser
 during a drag.

 @param inDragRef the native DragReference
 @param inSink the event sink to which the event will be dispatched

void leave(in DragReference inDragRef, in nsIEventSink inSink)

 Call when the mouse is inside the rectangle bounding the browser
 during a drag. The return value indicates if Gecko would accept the
 contents of the drag if a drop were to happen with the mouse in the
 current position. This can be used for doing some rudimentary drop
 feedback.

 @param inDragRef the native DragReference
 @param inSink the event sink to which the event will be dispatched

 @result <code>PR_TRUE</code> if the drag would be accepted by Gecko.

boolean tracking(in DragReference inDragRef, in nsIEventSink inSink)