Just thought I'd throw this out there for thought...
Have you considered basing the ItemsCollection off of System.Web.UI.WebControls.WebControl?
I was just thinking that it'd be nice to be able to insert a control that isn't based off Ext into the mix. This would broaden the value of Coolite in my opinion.
For example...let's say I'd like to use WebGuage from Infragistic's NetAdvantage product in my application.
Chad