The MSDN documentation on WebBrowser Customization explains how to prevent new windows from being opened and how to cancel navigation. In my case, my application is hosting
You could try a different approach instead and physically add the attribute target="_blank"
to all tags in the rendered document.
This approach would involve waiting for DISPID_DOCUMENTCOMPLETE and then using IHTMLDocument3::getElementsByTagName() to fetch all of the anchor elements. You would then use IHTMLElement::setAttribute() to set target="_blank" on each of them.