GtkText and colors

[Matthias Moeller <mattes ice robin de>]

I'd like to have text with different colors in a GtkText widget,
but I always get:

** ERROR **: file gtktext.c: line 2922 (advance_mark_n): "n > 0"
IOT trap/Abort

Here is an example:

------------------------------------------------------------------
#include <gtk/gtk.h>

int
main (int argc, char *argv[])
{
    GtkWidget *window;
    GtkWidget *text;
    GdkColor blue = {0, 0, 0, 0xc000 }; 
    GdkColor red  = {0, 0xc000, 0, 0 };
     
    gtk_init (&argc, &argv);
    window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
    gtk_container_border_width (GTK_CONTAINER (window), 10);

    text = gtk_text_new(NULL, NULL);
    gtk_container_add(GTK_CONTAINER(window), text);

    gtk_widget_show(text);
    gtk_widget_show(window);

    gdk_color_alloc(gtk_widget_get_colormap(text), &blue);
    gdk_color_alloc(gtk_widget_get_colormap(text), &red);

    gtk_text_insert(GTK_TEXT(text), NULL, &blue, NULL, "blue\n", 5);
    gtk_text_insert(GTK_TEXT(text), NULL, &red, NULL, "red\n", 4);

    gtk_main ();
       
    return 0;
}

--------------------------------------------------------------------

Is there anything wrong? It works fine, when I use always the samme
color. I am using gtk+-SNAP-980622.tar.gz.

thanks, Matthias