Selectively opening a new window

Is there a way to achieve the following from a Windows API?

Supposing you have a line of HTML such as this:

Code:

---

<a href="http://www.somewhere.com" target="nwindow">Somewhere</a>

---

As any HTML coder knows, when you click a link formed using code such as that above, you'll get a window named "nwindow". The effect is that, if such a window exists, it will be repopulated with the site you're visiting but if no such window exists, a new one will be created.

I'm working on an application that uses ShellExecute() to open up a browser window. Basically, it creates a local HTML file and then opens it using ShellExecute().

If I pass the name of the HTML file to the API, the most recent browser window is 'taken over' by the HTML file being opened.

If I pass the path to the browser's executable to the API and the name of the HTML file as a parameter, you always get a new window open up.

I'd like to make it such that, if my app has already opened up a browser window, then it would be taken over by the results of the next run, but if it hasn't already opened a window, then a new one would be created. In other words, more or less exactly as it would if you followed an HTML link formed like the one above.

Any ideas? TIA!