Firefox tabs show up as indavidual windows on toolbar

When i pass over the icon of firefox on my toolbar at the bottom of the screen( unsure of its real name but the bar with the time and start icon) each and every tab shows up separately. just today i repartitioned my hardrive, and before the reinstall it only showed whatever windows were open, no matter how many tabs were in each.
If there is any way i can return it to the old state that would be fantastical, i find it much easier to keep track of my browser and the windows i have open

Thanks for any help in advance

If i have one window of Firefox open and two tabs within it, it still shows each tab when i highlight the icon on the task bar. i went and clicked all the happy little box's but haven't restarted my computer but that seems unnecessarily.

Thanks so much for the quick help. i know that i had trouble knowing how to describe my problem, so that's why i couldn't just Google it.