  document.addEventListener( "mouseup",   upHandler,    true );

  }

  WebBrowser.prototype.releaseMouseCapture = function( node, clickHandler, downHandler, moveHandler, upHandler ) {

	if( upHandler)
      document.removeEventListener( "mouseup",   upHandler,    true );
			
    if( moveHandler )
      document.removeEventListener( "mousemove", moveHandler,  true );
		
    if( downHandler )
      document.removeEventListener( "mousedown", downHandler,  true );
			
    if( clickHandler )
      document.remo