The problem is: Venkman turns on the debugging interface on browser startup so that it is active throughout the entire browser session. And that’s independent of whether you are actually using the debugger. The only way to turn off this behavior is typing the following command on the Venkman command line:
This will only work until you install a new extension or upgrade Firefox, after that the setting will be reset.
Why is Venkman doing something like this? The problem is apparently that Venkman cannot “see” scripts that were compiled while the debugging interface was inactive. So if you turn off start-up initialization Venkman will always start with an empty file list. You will need to reload the pages you want to debug to see something. Even with start-up initialization some XPCOM components will remain invisible. This is being caused by bug 480765 – I hope that the patch there lands soon and Venkman is adjusted as well then.