Prior to 2.4, GTK+ offered two widgets for the task of selecting one item from a list of options. #GtkOptionMenu presents the list of options as a menu while #GtkCombo presents them in a Windows-style list popup. The only difference between the two is that a #GtkCombo allows to manually edit the selected value, while the #GtkOptionMenu does not. In GTK+ 2.4, a unified API for list selection was introduced, with #GtkComboBox for the non-editable case and #GtkComboBoxEntry for the editable case. The selection of the display style — menu or list — is no longer done at the API level, but has been made themeable via the style property GtkComboBox::appearance.

Here is an example of a simple, but typical use of #GtkOptionMenu: GtkWidget *option_menu, *menu, *menu_item; option_menu = gtk_option_menu_new (); menu = gtk_menu_new (); menu_item = gtk_menu_item_new_with_label ("First Item"); gtk_menu_shell_append (GTK_MENU_SHELL (menu), menu_item); gtk_widget_show (menu_item); menu_item = gtk_menu_item_new_with_label ("Second Item"); gtk_menu_shell_append (GTK_MENU_SHELL (menu), menu_item); gtk_widget_show (menu_item); menu_item = gtk_menu_item_new_with_label ("Third Item"); gtk_menu_shell_append (GTK_MENU_SHELL (menu), menu_item); gtk_widget_show (menu_item); gtk_option_menu_set_menu (GTK_OPTION_MENU (option_menu), menu); In order to react to the user's selection, connect to the "changed" signal on the option menu and use gtk_option_menu_get_history() to retrieve the index of the selected item. And here is how it would be done with a #GtkComboBox: GtkWidget *combo_box; combo_box = gtk_combo_box_new_text (); gtk_combo_box_append_text (GTK_COMBO_BOX (combo_box), "First Item"); gtk_combo_box_append_text (GTK_COMBO_BOX (combo_box), "Second Item"); gtk_combo_box_append_text (GTK_COMBO_BOX (combo_box), "Third Item"); In order to react to the user's selection, connect to the "changed" signal on the combo box and use gtk_combo_box_get_active() to retrieve the index of the selected item. A slightly more complex example involving images: GtkWidget *option_menu, *menu, *menu_item; option_menu = gtk_option_menu_new (); menu = gtk_menu_new (); menu_item = gtk_image_menu_item_new_with_label ("First Item"); gtk_image_menu_item_set_image (gtk_image_new_from_pixbuf (pixbuf1)); gtk_menu_shell_append (GTK_MENU_SHELL (menu), menu_item); gtk_widget_show (menu_item); menu_item = gtk_image_menu_item_new_with_label ("Second Item"); gtk_image_menu_item_set_image (gtk_image_new_from_pixbuf (pixbuf2)); gtk_menu_shell_append (GTK_MENU_SHELL (menu), menu_item); gtk_widget_show (menu_item); menu_item = gtk_image_menu_item_new_with_label ("Third Item"); gtk_image_menu_item_set_image (gtk_image_new_from_pixbuf (pixbuf3)); gtk_menu_shell_append (GTK_MENU_SHELL (menu), menu_item); gtk_widget_show (menu_item); gtk_option_menu_set_menu (GTK_OPTION_MENU (option_menu), menu); can be done using a #GtkComboBox as follows: GtkListStore *store; GtkTreeIter iter; GtkCellRenderer *renderer; GtkWidget *combo_box; store = gtk_list_store_new (2, GDK_TYPE_PIXBUF, G_TYPE_STRING); gtk_list_store_append (store, &iter); gtk_list_store_set (store, &iter, 0, pixbuf1, 1, "First Item", -1); gtk_list_store_append (store, &iter); gtk_list_store_set (store, &iter, 0, pixbuf2, 1, "Second Item", -1); gtk_list_store_append (store, &iter); gtk_list_store_set (store, &iter, 0, pixbuf3, 1, "Third Item", -1); combo_box = gtk_combo_box_new_with_model (GTK_TREE_MODEL (store)); renderer = gtk_cell_renderer_pixbuf_new (); gtk_cell_layout_pack_start (GTK_CELL_LAYOUT (combo_box), renderer, FALSE); gtk_cell_layout_set_attributes (GTK_CELL_LAYOUT (combo_box), renderer, "pixbuf", 0, NULL); renderer = gtk_cell_renderer_text_new (); gtk_cell_layout_pack_start (GTK_CELL_LAYOUT (combo_box), renderer, TRUE); gtk_cell_layout_set_attributes (GTK_CELL_LAYOUT (combo_box), renderer, "text", 1, NULL);

Here is an example of a simple, but typical use of a #GtkCombo: GtkWidget *combo; GList *items = NULL; items = g_list_append (items, "First Item"); items = g_list_append (items, "Second Item"); items = g_list_append (items, "Third Item"); combo = gtk_combo_new (); gtk_combo_set_popdown_strings (GTK_COMBO (combo), items); In order to react to the user's selection, connect to the "changed" signal on the combo and use gtk_entry_get_text (GTK_ENTRY (combo->entry)) to retrieve the selected text. And here is how it would be done using #GtkComboBoxEntry: combo_box = gtk_combo_box_entry_new_text (); gtk_combo_box_append_text (GTK_COMBO_BOX (combo_box), "First Item"); gtk_combo_box_append_text (GTK_COMBO_BOX (combo_box), "Second Item"); gtk_combo_box_append_text (GTK_COMBO_BOX (combo_box), "Third Item"); In order to react to the user's selection, connect to the "changed" signal on the combo and use gtk_entry_get_text (GTK_ENTRY (GTK_BIN (combo_box)->child)) to retrieve the selected text.

The new widgets have more to offer than a mere combination of the features of #GtkOptionMenu and #GtkCombo. Notable new features include: Grid mode Sometimes it is preferable to display the available options not in a linear list, but in a grid. A typical example would be a "color combo" where the individual items are small square color swatches. The new widgets support gridded display with the functions gtk_combo_box_set_wrap_width(), gtk_combo_box_set_row_span_column() and gtk_combo_box_set_column_span_column(). Display of icons An often-heard complaint about #GtkOptionMenu is that the icons which appear in the image menu items in its menu are not displayed in the button showing the selected item. This limitation has been removed in #GtkComboBox; the selected item appears in the same way as the options in the popup. Full tree model power Since the new widgets are built around the same models that are used for #GtkTreeView, all of the powerful machinery of tree models and cell renderers can be used.