This might be a little more involved for some but I have found a fix that works for me. It does require editing the wp-ui.js file of the plugin. This file is located in the wp-ui plugin folder within the js folder. The plugin actually uses a compressed version so I ended having to modify the wp-ui-dev.js file. The problem is on line 677 of this file. The current code looks like this:
_create : function() {
self = this;
$this = this.element;
this.o = this.options;
this.header = $this.find( this.o.header );
this.id = $this.attr( 'id' );
The problem is with the self = this; line and in Internet Explorer the “Not implemented error” occurs because self is a property of the window object. Using the var keyword (var self = this;) fixes the error.
Once you edit that line and saved the file you’ll need to rename the current wp-ui.js to something else (I renamed it to wp-ui-broken.js) then rename the wp-ui-dev.js to wp-ui.js so that the plugin will now use this modified file.
This fixed the accordion functionality in IE for me… hopefully it will work for others.
