setComponentIndex bugfix

Author: ianharrigan

haxe/ui/backend/ComponentImpl.hx

@@ -351,10 +351,16 @@ class ComponentImpl extends ComponentBase {
     }
 
     private override function handleSetComponentIndex(child:Component, index:Int) {
-        if (index == cast(this, Component).childComponents.length - 1) {
+        if (index == this.childComponents.length - 1) {
             element.appendChild(child.element);
         } else {
-            HtmlUtils.insertBefore(cast(this, Component).childComponents[index + 1].element, child.element);
+            if (index == this.childComponents.indexOf(child) - 1) {
+                var before = this.childComponents[index];
+                HtmlUtils.insertBefore(before.element, child.element);
+            } else {
+                var before = this.childComponents[index + 1];
+                HtmlUtils.insertBefore(before.element, child.element);
+            }
         }
     }