It doesn't matter to my scheme that they are built at different times: at the time that the Fx part builds its branding, it knows what version it wants to be, and it can preprocess branding/content/version.dtd, #expand <!ENTITY app.version "_MOZ_APP_VERSION_">, and then all about.xhtml has to know is include chrome://branding/content/version.dtd, and use &app.version; where it wants to put the app version number.
It doesn't matter to my scheme that they are built at different times: at the time that the Fx part builds its branding, it knows what version it wants to be, and it can preprocess branding/ content/ version. dtd, #expand <!ENTITY app.version "_MOZ_APP_ VERSION_ ">, and then all about.xhtml has to know is include chrome: //branding/ content/ version. dtd, and use &app.version; where it wants to put the app version number.