Standard docType for RootPanel and RootLayoutPanel in GWT

I used TabLayoutPanel widget in my GWT project but it is not working in ie. somewhere i read if i use RootLayoutPanel instead of RootPanel it will work. but for usnig RootLayoutPanel I should use some standard doctype in my html page.

which of docty开发者_如何学JAVApe i can use in my GWT project?

RGDS

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See here for the GWT 2.0 layout system.