Comment 3 for bug 196493

(Spotted on Ubuntu Hardy (8.04 development branch) using the latest trunk nightly from Mozilla.)

When Firefox sets itself as the default browser on Gnome, the command it uses to invoke itself is:
/path/to/firefox "%s"

Then, when Firefox is invoked from the keyboard shortcut (set in Gnome's System → Preferences → Keyboard Shortcuts), Firefox loads the user's home folder as a directory listing (i.e. it loads file:///home/example/ ).

Instead, Firefox should open a new window, as if it had been invoked from the Applications menu or a launcher. This can be achieved by changing the command used to invoke Firefox from the above to:
/path/to/firefox %s
i.e. by removing the quotation marks (users can do this in System → Preferences → Preferred Applications → Internet).

The in-built version of Firefox in Ubuntu invokes itself using:
firefox %s
so removing the quotes shouldn't have any unforeseen repercussions.

So: Firefox should register itself as the default browser using:
/path/to/firefox %s
instead of
/path/to/firefox "%s"

(I suppose other distros will also set this command themselves for the Firefoxen they distribute, which is why I've set this bug's severity to minor. I also reported this to Launchpad; detailed steps to reproduce are at https://bugs.launchpad.net/bugs/196493 )