> Couldn't the person who wants to use #display just write the 
> gif/jpg/png/pdf/etc.. then pass in the path to the file and make a call 
> to IE, Firefox, Netscape, etc...to open it?
> 
> It can't be that hard to figure out the default web browser.

No need to find out the browser.
`start filename`
works fine if it is enough to use whatever program it is that is 
associated with the file in question.