[Project_owners] Communicating between browser instances

Mook mook.moz at gmail.com
Sun Jan 15 13:44:01 EST 2006

On 1/15/06, Steven D Tine <stevetine at yahoo.com> wrote:
> I'm going to apologize up front if the question I'm
> asking is very basic but I'm new to extension
> development and JavaScript.
> It appears that each instance of the browser (e.g.
> when I choose 'File->New Window' or ctrl-n, a new
> browser window opens) has a unique copy of the
> extension code running it.  So, for example, the
> SwitchProxy extension (not my extension, but an easier
> example to describe than my extension) has an icon in
> the status bar.  When you click the icon, it
> alternates between red (no proxy configured) and green
> (proxy configured).  The problem is that when you have
> two browser windows open, the status bar is not in
> sync between the two windows.  By that I mean, when
> you click the icon in one window, the other window is
> not updated and the instance of the code in that
> window does not know that a change happened, so one
> window shows red and one shows green but obviously
> there is only one proxy setting for both windows so
> one window is wrong.  Is there a way for the code in
> the first instance to notify the code in the other
> window instances that a change was requested and
> completed?
> And to clarify my question, I don't just want to
> update the icon, but actually somehow notify my code
> in the other instance to update some state and then
> update the icon.
> I searched the archives for this mailing list and I
> found Eric Jung posted this code:
<snip code using nsIWindowMediator>

In the case of proxy settings, it probably modifies some preferences
to tell Firefox which proxy to use; thus it would probably make sense
to have a pref observer to update the icons (which would also mean
that if you modify them via Firefox options or about:config they'd
notice that too).  See:


Strangely, I can't find a devmo or kb.mz.org article on this...

If it's not prefs, you'd probably use a XPCOM service (i.e. make your
own XPCOM component and use .getService() to get it instead of
.createInstance()); that gets the same instance of your component
every time (and thus it's shared between windows).  Combined with an
observer (like the pref one, but with a different topic), it should
work just as well.

HTH :)
mook.moz at gmail

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