On Thu, May 17, 2018 at 8:58 AM, Stephan Bergmann <sbergman@redhat.com> wrote:

On 17/05/18 06:48, Chris Murphy wrote:

But, if I have the usual Fedora included Firefox running, and use that
same command, I merely get a new window. Going to the menu to Help and
About indicates it's not Nightly. There's no flatpak error to indicate
it didn't or can't launch Nightly.

I would guess that that's a generic feature of FF, unrelated to Flatpak:  If an instance of FF is already running, a new invocation just forwards to the existing instance.  So it would be bugs/mis-features of FF that (a) invocations of Flatpak'ed FF forward to an already running non-Flatpak'ed FF instance, and (b) invocations of FF with --safe-mode (Flatpak'ed or not) silently forward to an already running non--safe-mode FF instance.

--no-remote or --new-instance can be used to avoid re-using existing widows. Of course now that we have flatpaks and people can easily end up with several different firefox installations, it would be nice if this worked out of the box.