Using geckofx with vb.net to trigger web page event

Hi! - sorry if this is not quite the right place to post this, but it seemed the best bet.

I'm trying out geckofx to embed the browser in a form, navigate to a url, enter text in a few form fields, click buttons and the like.

All going well until I tried to use a dropdown box on a web site which had a change event. I can assign a text value to it with a bit of javascript. This selects the 4th option from dropdown called DDLStatus:

Code:

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GeckoWebBrowser1.Navigate("javascript:void( document.getElementById( 'DDLStatus' ).selectedIndex='4' )")

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What I can't do though is trigger the event which usually fires when the you pick an option from the dropdown on the web page.

Is there a simple way to do this? I thought something like this would work, but no joy:

Code:

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GeckoWebBrowser1.Navigate("javascript:void( document.getElementById( 'DDLStatus' ).change() ) ")

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I really don't know anything much about javascript, I've just got this far by googling, so there's a better way of doing this with geckofx directly that would be just fine.