Issue with HtmlEditor in FF 10.0 version

I am using EXTJS 3.0 in our Application. I am displaying a form panel inside window. I am using HTML editor in form panel. While placing cursor in the editor working fine in FF 3.6. But in FF 10.0 its throwing error saying

uncaught exception: [Exception... "Component returned failure code: 0x80004003 (NS_ERROR_INVALID_POINTER) [nsIDOMHTMLDocument.queryCommandState]" nsresult: "0x80004003 (NS_ERROR_INVALID_POINTER)" location: "JS frame :: ext-all-debug.js :: :: line 58124" data: no]

And the cursor is not placing in the editor.

What may be the issue with version?

Here is the code i have written in my java script file

**var test = new Ext.form.HtmlEditor({

    id:'testing',
    name:'tests',
    fieldLabel:'Test',
    width:200,
    height:150,
    allowBlank:false,
    enableColors : true,
        enableFont : false,
        enableFontSize: true,
        enableFormat: true,
        enableLists: true,
        enableSourceEdit: false,
        listeners: {
       sync: function(f){

     }
    }

});** Please Help me to get rid of this browser issues

Thanks & Regards

Bindu

HighRadius