This is probably a good site to be aware of http://www.accessfirefox.org/Firefox_Accessibility_Extensions.php It is a semi official mozilla community run site. IIRC the site and many of its addons were caught out by Australis. That is probably one site we should reach out to in advance if for instance making anything less distinct smaller, or lower contrast.

Thanks for the fast response FredMcD. This looks to be the perfect solution. I have downloaded a file called 'colorfultabs-30.0.1-sm+fx.xpi', but can't see how to use it. I am running XP, which says it can't open it, and when I tell it to search for a suitable program, it says 'This file in your language is not yet available.' Selecting 'View the English version.' just gives the same page again. Please can you tell me what am I missing? Panjang.

Sorry, FredMcD, that was a knee-jerk reaction. I have found the answer by putting my question in the search box. I have installed the ColourTabs add-on, and it is exactly what was needed. Thanks very much for your help. Panjang.

Thanks for posting back Panjang. I am glad the problem was solved.

For anyone else reading this thread note that to install an .xpi addon on Firefox you need to open that .xpi file with Firefox. Try either right clicking the .xpi file and looking for an option to open with Firefox; or whilst in Firefox use the Keyboard Shortcut Ctl + O (Cmd+O on a Mac ) to get the option to navigate to and open a file.

Glad to help. Safe Surfing.