This approach might help you:
http://stackoverflow.com/questions/9110388/web-browser-control-how-to-capture-document-events[
^]
It looks, like WPF WebBrowser control is facing even vorse flaws than the Windows Forms version. The concept of the solution on the link is to directly hook into the DOM with an event handler created on your app side.
Please note the comment below the accepted solution. It is linking here:
http://www.codegain.com/articles/wpf/ieprogramming/working-with-webbrowser-in-wpf.aspx[
^]. There are many interesting things, but you should look at
Invoke C# method from Javascript section. In your case this could be an even better approach, since you are using the browser control only as a layout engine.
But you might consider taking an other path: you have a layout engine already, WPF itself! Just recreate your local html as xaml, and load it from code in a container. And you have everything you need, even more.