Firefox Hacks [Electronic resources] نسخه متنی

Hack 85. Study Packages with the Chrome Manager

Demystify the way the chrome system is
organized with this handy tool.

The XML dialect called RDF is not exactly a simple system to use, and
Firefox relies on RDF files a lot. This hack shows how to use the
Chrome
Manager tool, an extension that provides a simple breakdown of these
complex structures. Together with the InfoLister extension [Hack #38], you can get a complete
picture of what's installed in the chrome.

8.3.1. Get the Chrome Manager

This useful extension is buried where it's hard to
find. It's written by Karsten Düsterlo as
part of the larger and cryptically named
Mnenhy extension.
"Mnenhy" stands for
Mail-News
ENHancement-Y. Whatever.
You can install it from here:

http://mnenhy.mozdev.org/

The beauty of this extension is not its mail and news features any
more than it is its cryptic name. Its beauty is in the small Chrome
Manager tool that's included almost as an
afterthought. Mnenhy can be safely installed as an extension in
Firefox, but at the time of writing (at Version 0.7), not all of its
features are complete or reliable. You've been
warned. It is safe to use as a view-only tool; don't
make changes with it unless you are an expert.

8.3.2. Chrome Simplified

Figure 8-1 shows the initial window that the Chrome
Manager presents.

Figure 8-1. The Chrome Manager window, with highlighted danger buttons

It's strongly recommended that you
don't push any of the buttons
circled in Figure 8-1. You might regret it if you
do. Avoid the temptation, or else study the online help before diving
in
bravely.

What's important about this window is the division
of all the chrome that Firefox possesses into three simple
categories: packages, skins, and locales. In the end, these things
are all that the chrome has to offer and all that can be accessed
using the special chrome: URL. So, all the
confusion about themes, skins, extensions, locales, and so on is
really just matter of labels; all these things boil down to those
three simple categories.

This display is derived from all the aggregated RDF information that
Firefox keeps in memory [Hack #75]
while it's running.

8.3.3. Understand Packages

Figure 8-2 shows the packages
part of the chrome hierarchy opened up one level.

Figure 8-2. The Chrome Manager, showing packages

In Figure 8-2, underlined package names are
installed in the profile area. As you can see, all underlined
packages are named after an extension, and each extension adds
exactly one package. That's the normal case, but not
an absolute rule. If you bring up this display and scroll down,
you'll see that the Mnenhy
extension provides seven packages.

More interestingly, the package names that are marked as applications
are the ones that are provided with the default install of Firefox.
They reside in the install area, but they're still
just packages. In Figure 8-2, you can see the
browser package that is the main Firefox
interface, the help system, the Cookie Manager, the DOM Inspector,
and even a bit of leftover Netscape Communicator 4.x in the
communicator package. It hasn't
been completely deprecated yet. In short, the entire Firefox user
interface, including extensions, is just a set of packages. If this
window is rearranged and manipulated a little, Figure 8-3 results.

Figure 8-3. The Chrome Manager, showing contributed skins

Here, the relationship between
packages, locales, and skins is made
obvious. The browser package (Firefox itself, appearing at line 8) is
well supported by the five or so additional themes that have been
installed. There's a skin for the
browser package from each of those five themes,
plus the default theme's skin. The lesser-known
addneditcookies package has received no special
skins from those themes. That's the price of
obscurity. Fortunately, there's always a
global skin, and all packages can trivially
benefit from that. Similarly, the only locale that contributes to the
browser is the default of en-US (U.S. English).
The addneditcookies package has only that locale
as well, so that extension can't be installed in the
German version of Firefox; if it were, it would be missing the
required de-DE locale, and no text would appear in
its user interface. It should be enhanced.

8.3.4. Packages Versus Extensions

It's revealing to compare the Chrome Manager
with the report generated by the
InfoLister extension [Hack #38] .
The Chrome Manager reports on the low-level packages, locales, and
skins that make up all the user-interface content. The InfoLister
window reports the names of the products that delivered those
packages: extensions, plug-ins, and themes. It's the
latter information that's used to check for updates
across the Web. The lower-level information is what Firefox uses when
it needs to display a window or dialog box.