Cookies and the problems they cause

I often use the Ext state manager to automatically manage cookies for Ext widgets. This allows the application to 'remember' user settings such as window size, location etc. The only code required is :

 Ext.state.Manager.setProvider(new Ext.state.CookieProvider());

This is very powerful and simple to add to an application BUT it can cause a mountain of problems. I've been bitten twice. What sometimes happens is the cookies can end up being applied to the incorrect objects. It seems that when Ext creates DOM objects, if there is no explicit dom id, an id is created. This id is used by the cookie 'manager' to reference the objects that are monitored. This is fine, except when items are added or removed from the application. The auto generated id numbers are changed and the cookies are now referencing different objects. This problem occurs during the development process or when new application versions are released (widgets are added and removed).

How do we avoid this? Its quite simple. Just assign explicit id properties to ALL items you create. Just do this as a 'best practice'. By doing this, there are no auto generated ids and no danger of the manager referencing the wrong objects.