noob need help improve an addon

[josh att]

Hi,

I'm not a coder. I tried to improve the code of this addon, and I
successfully changed one function, but I failed to add another
funtion, it's too complicated for me.

I wonder if anybody would like to help change the code? Thus I don't
have to learn Javascript and XUL from scratch. If there's no such
thing in this group, just let me know.

The download link of the original addon:
http://ljbrwa.bay.livefilestore.com/y1p2SXgOY7PVmdlxQWIOdet3HH_f3c1MUELvZt_C47WtIOpl2hOx3LayibjHxaWfhs9-L3zsQLZeYBMMmBFEnNZYlB3dV18EQ33/sessionpage-0.2.1-mod20090310.xpi?download

In short, with this addon, every time you close firefox, it collects
all tabs and make a url list, this list is named by time. Thus days
later you'll get many lists. Next time you run firefox, the last list
is shown,(or you can switch any other list), you can visit all urls,
one url, or some of them. But if you wanna find a specific url, it'll
take some time, since you can't possiblly remember which list it was
in, since lists are named by time.....

My purpose is to improve this addon by:

1, instead of many lists named by time, use only one list, named
"HISTORY". Every time you close firefox, all tabs will be added to the
end of this list.

2, if there's the same url exists in the list already, don't add that
url, or even better, move that url to newer location (lower).

3, add a "x" button BEFORE each url, thus can delete any specific url
at any time from this list.

Thanks.