Eclipse's Package explorer background color follows windows theme. I want to change the color without changing windows' theme. Possible?

Install the "Eclipse 4 Chrome Theme" from http://marketplace.eclipse.org/content/eclipse-4-chrome-theme

Then you can customize a lot of the Eclipse UI widgets. But not what you want, at least not out of the box. For that you should go to the CSS tab (in Eclipse 4 Chrome Theme) and paste this:

Tree, List, Table {
  background-color: #202020;
  color: #d0d0d0;
}

You can change almost anything, the problem is finding out what, and the fact that some things are bitmaps that you can't change (so if the bitmap is dark and you set a dark background you will "loose" the bitmap)

This list of widgets might help, http://download.eclipse.org/rt/rap/doc/1.5/help/html/reference/theming/index.html but they give you generic info on the widget names, not the Eclipse info (with IDs and all), so be careful :-)

== Very late addition ==

Everything you need in one place, including links to a custom dark theme: http://mihai-nita.net/2013/09/19/dark-eclipse/

Mac Screen Shot Example as of Sept 2013 (please be sure to restart Eclipse after changing file):

Just search "Theme" in the Eclipse Market Place. Install Moonrise. (Should be first option). Then go to the General, appearance, Click on appearance, change theme to moonrise, Then there you go.

Knowing the way the workbench is built, I'm sure your request is not possible on the Eclipse side. You can do this for the editors, because they are StyledText widgets, and you are exposed some preferences to customize these. The other views are various widgets, some are Trees, some are Text, some are composed from various other widgets. All of them are created with the default constructor which just uses the Windows theme.