name1: color1
name2: color2
... Color names must be acceptable as identifiers in the gtkrc syntax, and color specifications must be in the format accepted by gdk.color.Color.parse.Note that due to the way the color tables from different sources are merged, color specifications will be converted to hexadecimal form when getting this property.
Starting with GTK+ 2.12, the entries can alternatively be separated by ';' instead of newlines:
name1: color1; name2: color2; ...