Ext.form.ComboBox.prototype.onDestroy = function(){
        if(this.view){
            //this.view.setStore(null);
            this.view.el.removeAllListeners();
            this.view.el.remove();
            this.view.purgeListeners();
        }
        if(this.list){
            this.list.destroy();
        }
        if(this.store){
            this.store.un('beforeload', this.onBeforeLoad, this);
            this.store.un('load', this.onLoad, this);
            this.store.un('loadexception', this.collapse, this);
        }
        Ext.form.ComboBox.superclass.onDestroy.call(this);
};

Ext.form.ComboBox.prototype.updateSize = function() {
	this.setSize(this.width||'', this.height||'');
	this.list.setWidth(this.listWidth || Math.max(this.wrap.getWidth(), this.minListWidth));
};

Ext.form.ComboBox.prototype.onTypeAhead = function(){
    if(this.store.getCount() > 0){
		var r = this.store.getAt(0);
		var newValue = r.data[this.displayField];
		var hiddenValue = r.data[this.valueField];
		var len = newValue.length;
		var selStart = this.getRawValue().length;
		if (selStart != len) {
			//this.setRawValue(newValue);
			/* added by om *///this.lastSelectionText = newValue;
			this.setValue(hiddenValue);

			this.selectText(selStart, newValue.length);
		}
    }
};