Sorry about the snag here, @cschriemer.
The mockup name macro only works in controls that support text formatting - that’s why it’s not working in the browser.
But, that being said, I can totally see how it would be useful to use mockup-name in the browser’s title bar. I’m going to file the feature request, and we will talk about it.
A potential workaround would be to create a symbol with a browser and label control. Make the title (or URL) of the browser blank, and then overlay the label with the mockup-name macro. That way you have a customizable browser control that uses the mockup-name macro.
Hopefully that helps for now. We will see what we can do about allowing mockup-name in more places