Taking a look at my correspondence below, can anyone add any comments to help me
with 3 add-ons to Thunderbird?

How to install an add-on?

ME: Being new to Ubuntu, I am trying to fix "send without the subject" in
Thunderbird. I already downloaded
"/home/dan/Downloads/allow_empty_subject-0.3-tb.xpi" but don't know how to
install it in Thunderbird.

HELPER: I think that you can simply drag and drop the *.xpi file into the
Thunderbird Add-ons window. Alternatively, you can also use the little arrow
near the gears, choose "Install add-on from a file" and select your xpi.

ME: Hit install button to install xpi file and it came back with a warning "Not
Compatable with Thunderbird 3.0." I have downloaded Firefox 5.0 tar but don't
know how to install it from my download folder and I Don't see the little arrow
near the gears you were talking about.

HELPER: To install Thunderbird 5 in Ubuntu, follow these instructions:
http://support.mozillamessaging.com/e... and particulary the "Install the newest
release" chapter ;-) It will explain you how to set
ppa:mozillateam/thunderbird-stable

ME: Thank You VERY MUCH, kinda like the old DOS commands which I used to use.
Now that I have it updated I can install all my add-ons.
Thanks again for all your help....Dan

ME: Well, now after installing Thunderbird 5.0 I find that
1. contacts_sidebar-0.7.1-tb.xpi
2. allow_empty_subject-0.3-tb.xpi and
3. GMinder.msi
are also not compatible with Thunderbird 5.0

HELPER: Well, you need to wait that the author update its add-on to be
compatible with Thunderbird 5.

ME: Thanks, I'll try the three of them again next month. Just tried them this
this morning and they said they weren't compatible with 5.0.