We got some errors showing up in our logs that pointed to this piece of code in the src/dom/Element.position.js file:

Code:
    getPageBox: function(getRegion) {
        var me = this,
            el = me.dom,
            w = el.offsetWidth,
            h = el.offsetHeight,
            xy = me.getXY(),
            t = xy[1],
            r = xy[0] + w,
            b = xy[1] + h,
            l = xy[0];

        if (!el) {
            return new Ext.util.Region();
        }
...
Now, by looking at this code snippet above, the experienced coder should find out what could cause the "undefined" error. My guess is that someone was overly excited at optimizing code and just put all variables into the var region without checking.

If el is undefined, this code will throw an error in the vars section. It is being checked later on, but it will never reach it anyway since the error would already have been thrown.

Please change the code to show the following in order to fix this:

Code:
    getPageBox: function(getRegion) {
        var me = this,
            el = me.dom;

        if (!el) {
            return new Ext.util.Region();
        }

        var w = el.offsetWidth,
            h = el.offsetHeight,
            xy = me.getXY(),
            t = xy[1],
            r = xy[0] + w,
            b = xy[1] + h,
            l = xy[0];
...
I hope this will be fixed before the GA release. Thank you.