Comment 4 for bug 827904

here's a sequence of steps to reproduce, on Oneiric installed from 20110824 image, which I'm running on a virtual machine:

1- open a terminal.
2- Launch checkbox-gtk.
3- Deselect all tests.
4- Select a few quick tests (the Disk suite for instance).
5- Go through the run, even if you just click "next" on all the tests.
6- On the view report screen, click on "View Report" which should launch a browser.
7- Close the browser, then click on "Next" on the Checkbox window.
8- When you get the "Error" dialog about Launchpad submission, close it.
9- On the "Successfully finished testing!" screen, press "previous".
10- Click on "View report" again, and close the Firefox window that pops up.
11- At this point, hovering over the Checkbox window often (but not always) launches a new Firefox instance.
12- If things start behaving correctly (heh), repeat steps 7-10 to make it misbehave again.

One observation is that, if I tail the checkbox log (~/.cache/checkbox/checkbox.log), I see no change when the stray browsers are launched. This means that it's not the checkbox core's fault, but rather the GTK interface's code, so the place to look in might be gtk_interface.py and possibly the hypertext-aware component, hyper_text_view.py.