I am using Multi-Containers in Firefox and loving the feature so far. The only issue I am having is the inconsistency of the menu options when clicking the addon on the toolbar and on the address bar. The former has more options and the latter has only the "Always Open This Site In". For me, I want to have a setting to make the addon button on the address bar the same menu options as the addon on the toolbar. This way, I can see consistency when clicking around.
