Firefox apparently does not allow users to designate Tabs to open upon Start-up. It re-opens the tabs that were open on the previous session. Sometimes a second Firefox Window is opened either intentionally or unintentionally. The first Window is closed first at end of session, but the second Window is still open. When the second is closed, those Tab(s) re-open on the next session. This is frustrating because it is the first Window that I want re-opened in the next session. My taskbar on my laptop never alerts me how many Firefox Windows are open, so the frustration happens all too often. Please, let the user enter desired Tabs to be re-opened in the next session.