Warning: geeky stuff ahead. Sometimes I find myself getting prompted for a helper application when I click on weblog “subscribe” buttons. But I’m clicking because I want to look at the XML. Firefox’s dialog box doesn’t anticipate this, only giving me options to Open a helper application or to Save the XML to disk. There’s no “open here” or “view source”. Argh. Well, I found the trick: use Firefox itself as the helper application, and the XML opens up in a new tab. Bingo!