gistfile1.txt

Shell-1.0.gir:
      <function name="get_vertical_gradient"
                c:identifier="shell_global_get_vertical_gradient"
                doc="Creates a vertical gradient actor.">
        <return-value transfer-ownership="full">
          <type name="Clutter.Actor" c:type="ClutterActor*"/>
        </return-value>
        <parameters>
          <parameter name="top" transfer-ownership="none">
            <type name="Clutter.Color" c:type="ClutterColor*"/>
          </parameter>
          <parameter name="bottom" transfer-ownership="none">
            <type name="Clutter.Color" c:type="ClutterColor*"/>
          </parameter>
        </parameters>
      </function>

panel.js:
        let back_upper = global.get_vertical_gradient(PANEL_TOP_COLOR,
                                                      PANEL_MIDDLE_COLOR);
        log(back_upper);

shell-global.c:
/**
 * shell_global_get_vertical_gradient:
 *
 * @top: the color at the top
 * @bottom: the color at the bottom
 *
 * Creates a vertical gradient actor.
 *
 * Return value: a #ClutterActor with the gradient
 */
ClutterActor *
shell_global_get_vertical_gradient (ClutterColor *top, ClutterColor *bottom)
{
  ClutterActor *texture = clutter_cairo_texture_new (8, 8);
  return texture;
}