How to setup window's background color under Gnome

In current version of gnome, there is no tools for setting up background color of window, it's background setting only change desktop's background.

I really don't like white background, I want the background gray, so I setup some applications's background manually, but some application do not have background color setting(e.g. some versions of Eclipse), and it's not a good way to do that, so I spent little time on it.

First I tried some themes, some of them has gray background, while I don't like there colors setting, so what I need to do is to modify some themes to fit my requirement.

In gnome's theme setting -> Theme Details, you can choose different setting of Controls, window Border or Icons, window's background belongs to Controls, I picked up !LighthouseBlue as a base setting.

The themes file are under /usr/share/themes, I only modified gtk-2.0/gtkrc

bg[NORMAL] = "#D0D0D0" //background color of window
base[NORMAL] = "#CCCCC0" //background color or controls

That make me quite happy. I didn't find good tool for editing theme, there is a definition of the values: http://developer.gnome.org/doc/API/gtk/gtk-resource-files.html