I'm discovering that I need browser caching on page that I return to when the page that I am currently on contains a Back button with the definition: onclick="history.go(-1);". These pages are the pages containing DataGrids. These pages are cached sometimes with the wrong theme.

I know I can not redefine the Back button because I don't know the search criteria used to define the previous page.

Yes, that's (usually) correct. Many .NET controls perform a postback. When you'd reload a posted page, you get the browser's warning about resubmitting that page. This is to prevent you from submitting the same info twice. Since the browser can't distinguish between an order being paid twice, and a harmless move to another page on a GridView, this is a good thing.

As an alternative to the back button with history.go(-1), you could provide Back links / buttons that perform a redirect to the previous page. That way, the page is loaded again, without a browser's warning.

Does that help?

Imar
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Imar Spaanjaars
Everyone is unique, except for me.
Author of ASP.NET 2.0 Instant Results and Beginning Dreamweaver MX / MX 2004
Want to be my colleague? Then check out this post.

I was thinking of another approach to solve this problem. If I used the OutputCache directive with the "VaryByParam" attribute and add "theme=<color>" to all querystrings.

Can I append "&theme=<preferred theme>" or "?theme=<preferred theme>" string onto the querystring in an overrides Sub OnPreInit() call? I cannot find any documentation on when the OutputCache directive is processed and if it is processed after the OnPreInit method call.

This feels a bit weird and sounds like a lot of work.

Besides, it probably won't help. Since the page is cached by the browser, it never hits the server, so IIS / ASP.NET is never able to return a cached copy.

If I were you, I'd look into cache settings for your browser and your web server (IIS).

Cheers,

Imar
---------------------------------------
Imar Spaanjaars
Everyone is unique, except for me.
Author of ASP.NET 2.0 Instant Results and Beginning Dreamweaver MX / MX 2004
Want to be my colleague? Then check out this post.