code: function compareGrabberAndMousePosition(m) {
  			if (isScrollbarOver(m)) {
  				if (ctrl.horizontal) {
  					var start = getScrollbarArea().left + getGrabberOffsetPixelFromPercent(getGrabberOffsetPercentFromBegin($scope.ngBegin));
  					if (m.x < start)
  						return -1;
  					var end = start + getGrabberSizePixelFromPercent(getGrabberSizePercentFromScopeValues());
  					if (m.x > end)
  						return 1;
  					if (m.x >= start && m.x <= end)
  						return 0;
  				} else {
  					var start = getScrollbarArea().top + getGrabberOffsetPixelFromPercent(getGrabberOffsetPercentFromBegin($scope.ngBegin));
  					if (m.y < start)
  						return -1;
  					var end = start + getGrabberSizePixelFromPercent(getGrabberSizePercentFromScopeValues());
  					if (m.y > end)
  						return 1;
  					if (m.y >= start && m.y <= end)
  						return 0;
  				}
  			}
  			return Number.NaN;
  		}
docs: La souris est elle avant le grabber (-1), apres le grabber (1) sur le grabber (0), pas au dessus NaN
  @param {type} m
  @returns {Number}