code: function mousemove(event) {
                      // Prevent default dragging of selected content
                      event.preventDefault();
                      // Move helper
                      moveSelectionHelper(helper, startX, startY, event.pageX, event.pageY);
                      // Check items is selecting
                      var childs = getSelectableElements(element);
                      for (var i = 0; i < childs.length; i++) {
                          if (checkElementHitting(transformBox(offset(childs[i][0]).left, offset(childs[i][0]).top, offset(childs[i][0]).left + childs[i].prop('offsetWidth'), offset(childs[i][0]).top + childs[i].prop('offsetHeight')), transformBox(startX, startY, event.pageX, event.pageY))) {
                              if (childs[i].scope().isSelecting === false) {
                                  childs[i].scope().isSelecting = true;
                                  childs[i].scope().$apply();
                              }
                          } else {
                              if (childs[i].scope().isSelecting === true) {
                                  childs[i].scope().isSelecting = false;
                                  childs[i].scope().$apply();
                              }
                          }
                      }
                  }
docs: Method on Mouse Move
  @param  {Event} @event