Are there two different file tab shapes for some reason?
When I started using B6, the file tabs were sloped on the ends and overlapping each other.
When I did Zoom Toggle and then did View > Tool Windows > File Tabs, they had non-overlapping, squared ends.
I chose this option because I couldn't find Zoom Toggle when right-clicking in the Window. I later found it under the Window menu and this method results in getting the sloped/overlapping tabs.