Web lists-archives.com

Firefox 58.0.2 x64 & Portable 56.0.2, unable to open multiple Windows of installed version

This is on Windows 7 Pro (fully patched)...

Because of a critical legacy Addon (password manager, Passwordmaker),
I'm having to run a Portable version of 56.0.2 until I can decide which
way I'm going (probably moving to KeePass).

I also have the current stable version installed.

I need to be able to launch the Portable version when the installed
version is running, and I finally figured out how by setting
'AllowMultipleInstances' to true in the Portable version.

But, I just discovered that this prevents the installed version from
opening a second window (either manually, or when clicking a link from
an email (I have it set to open a new window on purpose).

Is there a way to set 'AllowMultipleInstances' on the installed version?
OR is there another way to do this that I'm missing when googling?

general mailing list