I don't do/know Macs. However, there is a way to get Firefox to save all your work and let you continue on from where you left off last.

Go to Tools -> Options. In the General tab, the very first section is called Startup and has a dropdown menu. Change the drop-down menu setting to "Show my windows and tabs from last time."

Hi, yes I know however this doesn't work if you press the red X button. It only works if you file -> exit from the menu bar which is different from native apps.

If you close windows before closing the Firefox application then you probably need to use "History > Recently Closed Windows" (Tabs) to reopen those windows or possibly "History > Restore Previous Session" if you have already closed Firefox.

Note that Firefox on Mac is supposed to turn to a native style in Firefox 24 (10.7 and up i think).

Firefox 24 being released today: http://www.mozilla.org/en-US/firefox/24.0beta/releasenotes/

Just tried it, its improved. Now it doesn't exit but "minimizes" to its icon, but when you restore it, no saved sessions.

Its progress so thanks!

Yes i dont think It will ever be 100% native, there used to be a Gecko based browser that used the native style of Mac, but is not secure anymore (Camino).

No problem, I appreciate this little advance and your reply.