This is perhaps my favorite bugfix/enhancement since... since they added the deletion of autocomplete results way back in March 2004.
Remember how hard it was to get links clicked in external applications to open in new tab? We tried setting the advanced.system.supportDDEExec preference to false (it worked spottily). We tried the Show Single Window extension which worked for awhile until something broke in Firefox (this time, I didn't bother to find out which bug this was exactly) and clicked links started opening in new windows. Tabbrowser Extensions worked, but there were times when it caused Firefox to break, and it isn't officially on u.m.o (update.mozilla.org).
Andy Mason wrote a comment recently to ask me how to get links from external applications to open in a new tab. I recommended Tabbrowser Preferences (TBP) - worked for him. Interestingly, this all happened today, just when the tabbed browsing preferences UI in bug 172962 - Options for where to open URLs from other applications (reuse tab, new tab, new window) that was mentioned in the TBP site went into the daily build. That's right, there's now a Tabbed Browsing preferences section in Firefox options as of today's daily build (2004-10-01) and this is how it looks like:
The first thing I did was uninstall the Single Window Extension to test it by selecting the radio boxes I highlighted in red and then going crazy with external application link-clicking. The verdict: it works beautifully! (Of course, I'm not an anal-retentive QA engineer, so there could be cases where it doesn't work that I've missed - but it seems to hold out pretty well for all my needs so far.) It may not seem like much a deal, but those of us who have been struggling with this will fully appreciate and understand the magnitude of this bugfix. Especially when this is one of the most often asked questions in the MozillaZine forums. I am so glad this is fixed.