docs: function handleMouseDown (e) {
                      if(enabled){
                          for (var i= 0; i<excludedClasses.length; i++) {
                              if (angular.element(e.target).hasClass(excludedClasses[i])) {
                                  return false;
                              }
                          }
  
                          $scope.$apply(function() {
                              onDragStart($scope);
                          });
  
                          // Set mouse drag listeners
                          setDragListeners();
  
                          // Set 'pushed' state
                          pushed = true;
                          lastClientX = startClientX = e.clientX;
                          lastClientY = startClientY = e.clientY;
  
                          clearSelection();
  
                          e.preventDefault();
                          e.stopPropagation();
                      }
  
                  }