How to open Model Dialogue as Popup on top of WebBrowser WPF

Question

<Grid>

<WebBrowser ></WebBrowser>

</Grid>

Now I want to add another child to the Grid which will be shown as a PopUp.

PopUp states WPF Model Dialogue This works at another Page but when I have a WebBrowser as a child in the Grid it is not working.

Now, my Question is How can I call the Model Dialogue on the

<WebBrowser >

....

</WebBrowser>

 

Control. 

Please Suggest me for Solution.

Replies always Welcome.