Maigre is a managed GTK theme engine. It allows easily writing GTK themes
in managed code. Maigre takes care of implementing the GtkRcStyle, GtkStyle,
and theme module entry points, leaving the theme author to only have to worry
about rendering code.

An example:

using System;

public class MyTheme : Maigre.Theme
{
    protected override void ModuleInit ()
    {
    }

    protected override void DrawBox ()
    {
        switch (Detail) {
            case "button":
                Cr.Rectangle (0, 0, Width, Height);
                Cr.Color = new Cairo.Color (0, 0, 0);
                Cr.Fill ();
                break;
            default:
                base.DrawBox ();
                break;
        }
    }
}