I have been using Thunderbird for over 15 years. I keep upgrading it to new versions. At one time, I had an ADD-ON or a theme that had my rows in the inbox highlighted alternately. In grey and white or in Blue and white. this made the Thunderbird very easy to read. Now with the new version 31, all of that is disappeared. I searched the Themes. the one that fits my requirement does NOT support the TB 31 ! why then upgrade if most of Add-ons or themes don't work with new versions of TB? and why do u keep the old add-ons on the website if they are out-dated and only work with older TB's? Shouldn't there be a warning " do not upgrade cause your favorite Add-ons wont work"?