how to change proxy settings with an external program

Hello,

My company develops a local proxy (currently win32 only). In this way,
we need to change the browser proxy setting to intercept http traffic.
I know I can change the prefs.js file, but this change needs that
NS/Mozilla be restarted.
So I'm looking for an API that I could use in my program to modify
dynamically the proxy settings. In this case, it could be possible for
users to disable/enable our local proxy without the need of restarting
the browser.

Does someone know if this API exists (a function in a mozilla dll, or a
mecanism that inform mozilla/ns it should reload the prefs.js file
because it has changed etc.) , and how to use it ?

Thanks,

Sylvain
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