If the Bookmarks library window is open and displaying then Firefox is still running.

Opening any bookmark, history item or folder from that library opens a new Firefox window.

I just think it's not that normal behavior to have to open a history item just so a window opens so you can get to another page...

anyway, thank you!

The more usual method may be to leave a Firefox window open and use tabbed browsing, rather than leaving just the History Library running whilst Firfox is otherwise not in use.

• see http://kb.mozillazine.org/Moving_your_profile_folder#Create_a_new_profile_and_migrate_your_old_data
  -- ^-- clickable link -- (blue) --

Also maybe you may consider working from Bookmarks rather than history, and note that Firefox may be set to start with the previous tabs reopening

• Bookmarks in Firefox _{(that is low in the search order for some reason)}
• session restore

Thanks again!