I guess you can fake an SSB in firefox by some hacking. I don't know how much work you want to put into this but here a sketch of an idea.
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Create a new Profile in firefox: open about:profilesclick in create new profile and give it the name of the SSB application you want to create.
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Open firefox in the new profile by running the command firefox --no-remote -P "ProfileName"
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Check if you are in the correct profile by opening about:support, in the information table look for Profile Directory. The path must end in "ProfileName". Click in Open Directory.