added optional insertBefore in utl.getDOMElement

lib/DOMutil.js

@@ -82,7 +82,7 @@ exports.getSVGElement = function (elementType, JSONcontainer, svgContainer) {
  * @returns {*}
  * @private
  */
-exports.getDOMElement = function (elementType, JSONcontainer, DOMContainer) {
+exports.getDOMElement = function (elementType, JSONcontainer, DOMContainer, insertBefore) {
   var element;
   // allocate DOM element, if it doesnt yet exist, create one.
   if (JSONcontainer.hasOwnProperty(elementType)) { // this element has been created before
@@ -94,14 +94,24 @@ exports.getDOMElement = function (elementType, JSONcontainer, DOMContainer) {
     else {
       // create a new element and add it to the SVG
       element = document.createElement(elementType);
-      DOMContainer.appendChild(element);
+      if (insertBefore !== undefined) {
+        DOMContainer.insertBefore(element, insertBefore);
+      }
+      else {
+        DOMContainer.appendChild(element);
+      }
     }
   }
   else {
     // create a new element and add it to the SVG, also create a new object in the svgElements to keep track of it.
     element = document.createElement(elementType);
     JSONcontainer[elementType] = {used: [], redundant: []};
-    DOMContainer.appendChild(element);
+    if (insertBefore !== undefined) {
+      DOMContainer.insertBefore(element, insertBefore);
+    }
+    else {
+      DOMContainer.appendChild(element);
+    }
   }
   JSONcontainer[elementType].used.push(element);
   return element;