Mac - navigateToURL opens default application for .html files instead of browser

On Mac I have Adobe AIR version <string>3.1.0.4880</string> and I have selected TextMate for .html file as default application. With this configuration when I call navigateToURL in my app to open browser, it opens TextMate instead of default browser.

Following is the simple code to open URL:

var urlRequest:URLRequest = new URLRequest(url);

navigateToURL(urlRequest, "_blank");

Is this known issue? Any workaround for this?

Thanks,