Problems with Naba Kumar's progress cell renderer

[Tilman Sauerbeck <tilman sauerbeck web de>]

Hi folks,
I'm trying to get Naba Kumar's progressbar cell renderer to work. The problem is setting the colors for the 
different progress stages:
low, med and high. I'm doing it the following way:

GdkColor color;
gchar *back;

color.red = color.green = color.blue = 0xffff;
color.red = 0xffff; color.green = 0; color.blue = 0;
low = util_gdk_color_to_string(&color); // this function is in util.c, in the same tarball as 
gtkprogresscellrenderer.c

g_object_set(G_OBJECT(renderer), "low-color", low, NULL);
g_free(low);

This basically works, too, but the progressbar always shows the "high" value, even when the progressbar isn't 
nearly filled, resp. it isn't filled at all. The bar draws correctly, i.e. my "high-value" and "low-value" 
values are set correctly (low: 0, high: 100), but the colors don't change.