What is the WPF equivalant of DocumentCompleted for the WebBrowser class?

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What is the WPF equivalant of DocumentCompleted for the WebBrowser class? The DocumentCompleted method does not exist in WPF (at least not in the latest version of .NET and visual studio). So how do I do the same thing that one could do with Windows Forms in WPF? This is a reoccuring thing. I find the need to have a methond in a C# class in WPF. Then I find that the methods are redone from Windows Forms to WPF and there is no supporting documentation to be found. Windows Forms C# seems to have its own set of APIs and Methods. WPF C# seems to have its own set of APIs and Methods. Silvelight C# seems to have its own set of APIs and Methods. I have wondered how developers navagate from one jungle to the next. If you want to do something in WPF and all you can find it examples of how to perform a task in Windows Forms, what is the trick to finding out the equivalent in an other API library?