How do I interact with element inside a WebViewer?

I am writing an app to wrap a web page. How do I fill in the form fields and click HTML buttons inside the WebViewer? I suspect I need to introduce write some custom Javascript to manipulate the site and use the RunJavaScript method, but how do I inject my JavaScript into the main page I didn't write?

the following example was written before that method was available... you might want to adjust it to your needs...
How to fill out a form of a webpage and click a button using some JavaScript


Trying to push the limits! Snippets, Tutorials and Extensions from Pura Vida Apps by icon24 Taifun.


I noticed that you used GoToUrl method for the WebViewer. I actually implemented the same JavaScript code by calling RunJavaScript method. Does it matter?

as already said earlier