Sometimes I switch back and forth between default browsers on Mac OS X. It seems strange to me that it is the browser itself that I inform of such policy decisions. That tells me and I would presume others, that a browser, or presumably any program, is allowed to change my preferences and that it need not consult be before doing so.

Perhaps one reason for this arrangement is that the issue at hand is what program to invoke when I click on an URL in an e-Mail agent or other non-browser application. The user presumably understands that there is more than one browser and there is thus a decision to be made upon such clicks. Since the user has the concept of multiple browsers, the browser is thus a good first guess of where to go to establish such policy. The idea is to say to one of the browsers, “Start up when some other application needs to defer to a full-fledged browser.”. There is an unspoken assumption that the software designer makes and assumes that the user understands: a previously anointed browser is thus displaced from this role.

I won’t belabor the point that if the browser can take this action then so presumably any other application. Here is how I would try to handle this in a capability UI system. I will illustrate by describing an ultra verbose narrative addressed to the user.

The user launches some browser and pokes around its controls until he finds something about default browsers. He invokes that function. A window pops up that says verbosely:

Hi, I am from the government (OS) and I am here to help you. Your browser, Firefox, tells me that you have asked that it be anointed as your default browser. This version of Firefox ( has been signed by the Mozilla foundation. I know nothing more about it. When you click on a link in some application that is not a browser then that application will conventionally invoke your default browser. Do you want this Firefox browser to be your dafault?

If you want to change your mind later you can contact me at:
Menu > Apple > Personal Preferences > Default Browser

You need not worry that I am an imposter for only I, you may recall, hold the authority to change your default browser.

The last sentence has a curious force of logic. The user must have learned from some other source that this is so. The reason to include the information here is to assure the user that his policy can be enforced. The default browser agent must be sure that it has a secure path to the user, but the user does not need assurance of the identity of the agent.

A point of less significance is verbosity. If this were a more common dialog box, it would need a shorter spiel but even then with on option for full disclosure.