Editing GTK theme (adding a border)

I am using a GTK theme which I love except that it doesn't have borders around the windows. If I am on a web page (for example) with a white background and my wallpaper is white I don't know where the web page starts. What is worse, sometimes that type of thing happens with other windows, where I can't tell where the one window start and the other ends.

Is there a way to edit GTK themes? More specifically, is there a way to edit a theme so that it will display a border around windows?

The window border width is actually set by the Metacity theme. You can either change the Metacity theme (System ➜ Preferences ➜ Appearance ➜ Theme ➜ Customize ➜ Window Border) to one that has a window border or edit the Metacity theme you are using right now.

Metacity theme files are located in ~/.themes/<theme name>/metacity-1/ and /usr/share/themes/<theme name>/metacity-1/.

Edit your theme's metacity-theme-1.xml file and change all values left_width,right_width and bottom_height to something higher than 0.

<distance name="left_width" value="2"/>
<distance name="right_width" value="2"/>
<distance name="bottom_height" value="2"/>