how to set line colour in libgoffice charts

[jcupitt gmail com]

Hello everyone,

I've just updated from 0.7.4 to 0.7.8 (the version that's packaged
with the current Ubuntu as v0.8) and my code can no longer set line
colours.

I made a tiny test program:

----------------
/* Compile with:

       gcc -g -Wall chart.c `pkg-config libgoffice-0.8 --cflags --libs`

 */

#include <gtk/gtk.h>

#include <goffice/goffice.h>

#include <goffice/app/go-plugin.h>
#include <goffice/app/go-plugin-loader-module.h>

#include <goffice/data/go-data-simple.h>

#include <goffice/graph/gog-data-set.h>
#include <goffice/graph/gog-label.h>
#include <goffice/graph/gog-object.h>
#include <goffice/graph/gog-plot.h>
#include <goffice/graph/gog-series.h>

#include <goffice/gtk/go-graph-widget.h>

#include <goffice/utils/go-color.h>

static double xes[] = { 1.0, 2.0, 3.0 };
static double yes[] = { 1.0, 12.0, 5.0 };

int
main (int argc, char **argv)
{
  GtkWidget *window;

  GtkWidget *graph;
  GogChart *chart;
  GogPlot *plot;
  GogSeries *series;
  GOData *data;
  GError *error;
  GOStyle *style;

  gtk_init (&argc, &argv);

  libgoffice_init ();
  go_plugins_init (NULL, NULL, NULL, NULL, TRUE,
                   GO_TYPE_PLUGIN_LOADER_MODULE);

  window = gtk_window_new (GTK_WINDOW_TOPLEVEL);

  graph = go_graph_widget_new (NULL);
  gtk_container_add (GTK_CONTAINER (window), graph);

  chart = go_graph_widget_get_chart (GO_GRAPH_WIDGET (graph));

  plot = gog_plot_new_by_name ("GogXYPlot");
  gog_object_add_by_name (GOG_OBJECT (chart), "Plot", GOG_OBJECT (plot));

  series = gog_plot_new_series (plot);
  data = go_data_vector_val_new (xes, 3, NULL);
  gog_series_set_dim (series, 0, data, &error);
  data = go_data_vector_val_new (yes, 3, NULL);
  gog_series_set_dim (series, 1, data, &error);

  style = go_styled_object_get_style (GO_STYLED_OBJECT (series));
  style->line.color = RGB_RED;
  style->line.auto_color = FALSE;
  gog_object_request_update (GOG_OBJECT (series));

  // tried this too
  // go_styled_object_style_changed (GO_STYLED_OBJECT (series));

  gtk_widget_show_all (window);

  gtk_main ();

  return 0;
}
--------------------

What's the recommended way to set a line colour in 0.7.8?

John