Qt SDK comes with the source code, for example QListWidget source can be found in: "C:\Qt\2010.05\qt\src\gui\itemviews" //i'm on windows now, with Qt 4.7
And i don't really understand your question, you want the help to display the source code and not the documentation?
I don't think that, in the majority of the cases, you need to see the source code to understand how to use a feature/function/class/module of Qt, it might help in some cases, but the documentation is better most of the times.
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