Problem if i add any panel / formpanel with title i get strange error only in Firebug (v1.6.2, otheres too).
In Firefox 3 and 4.

Sample code that generate such error:

Code:
Ext.onReady(function () {
    Ext.create('Ext.Panel', {
        title: 'title',
        renderTo: Ext.getBody(),
        items: {
            xtype: 'container',
            html: 'content here'
        }
    });
});
In Stack i have long history of render functions, that end up on 2 calls for evaluateFn:

Code:
evaluatedFn = function (values, parent, xindex, xcount) {return ["<div class=\"", values.baseCls === undefined ? "" : values.baseCls, "-body", this.applySubTemplate(0, values, parent, xindex, xcount), "\"", this.applySubTemplate(1, values, parent, xindex, xcount), "></div>"].join("");};
Then firebug stop page, if i continue, then all works fine and console has no errors.

I tried to run in other browsers and without firebug - all works good. And i don't have any problems with ExtJS3 on my browser setup.