code: func (v *ColorChooser) AddPalette(orientation Orientation, colors_per_line int, colors []*gdk.RGBA) {
  	n_colors := len(colors)
  	var c_colors []C.GdkRGBA
  	for _, c := range colors {
  		c_colors = append(c_colors, *(*C.GdkRGBA)(unsafe.Pointer(c.Native())))
  	}
  	C.gtk_color_chooser_add_palette(
  		v.native(),
  		C.GtkOrientation(orientation),
  		C.gint(colors_per_line),
  		C.gint(n_colors),
  		&c_colors[0],
  	)
  }
docs: // AddPalette() is a wrapper around gtk_color_chooser_add_palette().