A #GtkToolPalette allows you to add #GtkToolItems to a palette-like container with different categories and drag and drop support.

A #GtkToolPalette is created with a call to gtk.tool_palette.ToolPalette.new_.

#GtkToolItems cannot be added directly to a #GtkToolPalette - instead they are added to a #GtkToolItemGroup which can than be added to a #GtkToolPalette. To add a #GtkToolItemGroup to a #GtkToolPalette, use gtk.container.Container.add.

GtkWidget *palette, *group;
GtkToolItem *item;

palette = gtk_tool_palette_new ();
group = gtk_tool_item_group_new (_("Test Category"));
gtk_container_add (GTK_CONTAINER (palette), group);

item = gtk_tool_button_new (NULL, _("_Open"));
gtk_tool_button_set_icon_name (GTK_TOOL_BUTTON (item), "document-open");
gtk_tool_item_group_insert (GTK_TOOL_ITEM_GROUP (group), item, -1);

The easiest way to use drag and drop with #GtkToolPalette is to call gtk.tool_palette.ToolPalette.addDragDest with the desired drag source @palette and the desired drag target @widget. Then gtk.tool_palette.ToolPalette.getDragItem can be used to get the dragged item in the #GtkWidget::drag-data-received signal handler of the drag target.

static void
passive_canvas_drag_data_received (GtkWidget        *widget,
                                   GdkDragContext   *context,
                                   gint              x,
                                   gint              y,
                                   GtkSelectionData *selection,
                                   guint             info,
                                   guint             time,
                                   gpointer          data)
{
  GtkWidget *palette;
  GtkWidget *item;

  // Get the dragged item
  palette = gtk_widget_get_ancestor (gtk_drag_get_source_widget (context),
                                     GTK_TYPE_TOOL_PALETTE);
  if (palette != NULL)
    item = gtk_tool_palette_get_drag_item (GTK_TOOL_PALETTE (palette),
                                           selection);

  // Do something with item
}

GtkWidget *target, palette;

palette = gtk_tool_palette_new ();
target = gtk_drawing_area_new ();

g_signal_connect (G_OBJECT (target), "drag-data-received",
                  G_CALLBACK (passive_canvas_drag_data_received), NULL);
gtk_tool_palette_add_drag_dest (GTK_TOOL_PALETTE (palette), target,
                                GTK_DEST_DEFAULT_ALL,
                                GTK_TOOL_PALETTE_DRAG_ITEMS,
                                GDK_ACTION_COPY);

CSS nodes

GtkToolPalette has a single CSS node named toolpalette.