Installed this Ad-on and followed the developers instructions in downloading the additional Tab Mix Plus Dev Build. At first the the close button, scroll right and scroll left button did not appear. I then went to customize tool bar options and found the icons and placed them in the tool bar. Once in place the right & left buttons did not work at all. The close tab button worked properly though. Although the Left & Right buttons did not work I found their appearance unsatisfactory as they took up a lot of room in the tool bar, but that's just me. However, I did like the additions to the Tab Bar area; You are given an open new tab icon situated on the left side which is useful. Furthermore on the right side of the tab bar you are given display opened tabs icon that gives the user a window that displays a thumbnail of all opened tabs. This is a nice feature seeing you don't have to install another add-on. Finally I noticed that when you open a new tab it shows a progress bar within the tab as the page is loading which is a nice feature. I hope in the future the developer my shrink the size of the scroll buttons and it would be great to have them in the tab bar area as opposed to the tool bar. I feel if you have them all the way up there on the tool bar you are already passing over the tabs and why not click on them instead of going to the scroll buttons. having them in the tab bar allows the user to do less overall navigating with either a touch pad or mouse. If some of these issues are ironed out in the near future it will become a terrific add-on(5 stars), Yet at this point I rate it @ 3 stars based upon those aspects I favored and the momentary glitches @ this time. KEEP UP THE GOOD WORK!!!