+
+/**
+ * Is one element contained by another?
+ * @param {Element} containee The contained element.
+ * @param {Element} container The container element.
+ * @return {boolean} Whether containee is inside (or equal to) container.
+ * @private
+ */
+Dygraph.isElementContainedBy = function(containee, container) {
+ if (container === null || containee === null) {
+ return false;
+ }
+ while (containee && containee !== container) {
+ containee = containee.parentNode;
+ }
+ return (containee === container);
+};