Make sure your tabs stay visible all the time.
In addition, this addon let's you:
Disable tab open/close animations - for quicker tab resizing
Hide blank tab favicons - save precious space for the tab title
Hide close button from active tab; OFF by default
Slimmer pinned tabs - may be very useful if you have lots of pinned tabs.
Dim pending tabs - easily identify unloaded tabs
Reduce Firefox button width - save precious space in the tab bar; OFF by default
Use the Options page to personalize it to your needs.