using external JARs in Eclipse

In order to use external JAR files in Eclipse, the most robust way if
you develop on multiple platforms is to use "Preferences > Java > Build
Path > Classpath Variables" to add a classpath variable. You can give it
any name you wish, and you must associate to it the file name of the JAR
that you want to include.

import source code in eclipse

To import existing source code in Eclipse, do the following:
1) Create a new project and give it the same name with the directory
containing your source code.
2) Uncheck "Use default location" and manually set the location to the
directory containing the source code.
Usually Eclipse automatically detects your source code, and you can
simply click "Finish" to finalize project creation.

color code messages in thunderbird

In order to color message lines in the message pane in Thunderbird, you need to edit the CSS file "chrome/userChrome.css" in your profile directory. On Mac OS X this is located in "~/Library/Thunderbird/Profiles/xyz.default/". If the CSS file (or the chrome directory ) do not exist, create them.

A possible application is color coding replied messages. The code below uses green color to highlight them:

/*
 * Do not remove the @namespace line -- it's required for correct functioning
 */

/*
 * Set default namespace to XUL
 */
@namespace
url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");

/* background for normal message lines */
treechildren::-moz-tree-cell(replied) {
background-color: LightGreen !important;
}
/* background for current message line */
treechildren::-moz-tree-cell(replied,current) {
background-color: Green !important;
}
/* background for selected message lines */
treechildren::-moz-tree-cell(replied,selected) {
background-color: Green !important;
}

More examples can be found here:
http://www.eriwen.com/css/tweaking-thunderbirds-chrome/

show changes for a certain revision in svn

In order to show the source code changes for a certain revision "RVSN", use the following command:
> svn diff -c RVSN

hide tab in Thunderbird

In order to hide the tab in Thunderbird and increase the useful window area, set the option "mail.tabs.autoHide" to "true" by using the Config Editor (accessible from Preferences > Advanced > General). If more that one tab are created, then the area is displayed again.