Tab Color Underscoring active/read/unread

Install

Colors the bottom border of a tab with RED for active tab, BLUE for a normal tab, GREEN for a still unread tab. In other words distinguishes tabs as active tab, viewed tab, unviewed tab. Does not affect the background color of a tab so that color usage of "Perma Tabs" ("Perma Tabs Mod"), and/or "Multiple Tab Handler" extensions will prevail. Bottom border color will show up even if tabs on the tabs bar have been squeezed down so much that only the favicon can be seen.

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Please vote on getting Bug 487242 fixed to regain full benefits of this style in Firefox 3.6
https://bugzilla.mozilla.org/show_bug.cgi?id=487242

Test code can be found in Tab Color Underscoring active/read/unread (Fx3.6)
but you will need the TabVisited extension only found in Bug 487242
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An unread tab is one that has been opened in the background such as with a mouse shortcut, and will also be seen for tabs restored from a terminated session.

When a tab is opened in the background the current tab remains active (Ctrl+Shift+click)
When a tab is opened in the foreground the the new tab becomes active (Ctrl+click).
The mouse shortcuts that I use above are reversed from Firefox's default because I checkmark the option at Tools, Options, Tabs, [x] When I open a link in a new tab, switch to it immediately.

My method of reading most web pages is to stay within the article, opening links in the background at the far right of the tabs bar, when I have finished reading all of the originally selected pages, I start reading the new pages in the same manner, new tabs to the a right after all they are secondary material. I try not to build up layers within a tab, so that I can tell for sure when I am finished with a tab. Especially when reading Blogs where I start with several blogs by opening them from a folder on my bookmarks toolbar.

If "private browsing" for the active tab in particular can be determined might add an dotted black border at top of tab. [Unfortunately Private Browsing is all or nothing it is not per tab].
border-top: dotted 2px #FF6600 !important;

This style can be used together with Tabs Bar Minimal Size (9043) by David McRitchie.

Problem with Firefox 3.6 (Namoroka), visited tabs appear same as unvisited tabs both are showing green underscores. Works okay all versions through Firefox 3.5 (Shiretoko). [see Bug 487242] Please vote on getting the Bug fixed if you want to continue full benefits of this style in Firefox 3.6 and later. With the ordering of new tabs opened in the background in 3.6 you will really need to know which tabs have been visited or and which are unvisited.

Updates to code since 2008-07-24 (none)