Hi,

I want to pass a lot of different values to the BeforeEventRender method, in order to build up the display and apply various other options such as sidebar colours, it if can be moved, different menus etc.

This is possible using the DataTagFields setting, but from what I understand these option makes all the tags available to the client for use with JavaScript.

This would result in unnecessary information being sent to the client computer which has the following disadvantages.

1) Page size would be larger which could affect rendering speed or view state issues (especially with a lot of events)
2) Security issues - People may expose certain fields to the server side in order to perform the required actions, but may not want the user to gain access to these values by viewing code or running JavaScript.
I suggest you leave the current DataTagFields property (For people who need client side & server)
Add "DataTagFieldsServer" which wont expose the tag for use in JavaScript