Is it possible when closing a window with more panels to set to open them next time I run firefox?
Was possible in earlier versions.
Alla svar (1)
Firefox 4 and later versions save the previous session automatically, so there is no longer need for the dialog asking if you want to save the current session.
Use "File > Exit" or "Firefox > Exit" (Mac: "Firefox > Quit Firefox") if you want to restore multiple windows.
You can use "History > Restore Previous Session" to get the previous session at any time.
You may need to click the orange/gray Firefox button to see History.
There is also a "Restore Previous Session" button on the default about:home Home page.
Another possibility is to use:
- Firefox/Tools > Options > General > Startup: "When Firefox Starts": "Show my windows and tabs from last time"