How to create a GTK4 Dropdown that allows multiple selections?

Platform
1

Hey! I’m using the C/C++ API of GTK4, and I’m trying to create a simple GtkDropDown that displays a list of strings (this list is implemented through a GtkStringList model), and that allows “multiselection”. The dropdown works, but, I’m unable to select multiple items in the list at the same time. Only single selection works.

I tried to use GtkMultiSelection to fix this, but it is not working. Only single selection works still. I’ve isolated the problem in a minimal GTK4 application to make a reproducible example. If you compile and run the example below, you will see a dropdown that allows only single selection. So my question is how can I change this minimal example to create a dropdown that allows multiple selections?

#include "gtk/gtk.h"

GtkStringList*
create_stars_items_list() {
  GtkStringList* list = gtk_string_list_new(
        (const char* const[]){"0", "1", "2", "3", "4", "5", NULL}
    );
  return list;
}

static void
setup_stars_listitem_cb(GtkListItemFactory* factory, GtkListItem* list_item) {
    GtkWidget* widget = gtk_label_new("");
    gtk_list_item_set_child(list_item, widget);
}

static void
bind_stars_listitem_cb(GtkListItemFactory* factory, GtkListItem* list_item) {
    GtkWidget* widget = gtk_list_item_get_child(list_item);
    GtkStringObject* string = (GtkStringObject*)gtk_list_item_get_item(list_item);
    gtk_label_set_text(GTK_LABEL(widget), gtk_string_object_get_string(string));
}

static void
activate(GtkApplication* app, gpointer user_data) {
  GtkWidget *window;

  window = gtk_application_window_new (app);
  gtk_window_set_title (GTK_WINDOW (window), "Window");
  gtk_window_set_default_size (GTK_WINDOW (window), 200, 200);
  gtk_window_present (GTK_WINDOW (window));

  GtkStringList* stars_list = create_stars_items_list();
  GtkMultiSelection* stars_selection = gtk_multi_selection_new(G_LIST_MODEL(stars_list));
  GtkListItemFactory* stars_factory = gtk_signal_list_item_factory_new();
  g_signal_connect (stars_factory, "setup", G_CALLBACK(setup_stars_listitem_cb), NULL);
  g_signal_connect (stars_factory, "bind", G_CALLBACK(bind_stars_listitem_cb), NULL);

  GtkWidget* stars_dropdown = gtk_drop_down_new(G_LIST_MODEL(stars_selection), NULL);
  gtk_window_set_child(GTK_WINDOW(window), stars_dropdown);
}

int main(int argc, char** argv) {
  GtkApplication *app;
  int status;

  app = gtk_application_new ("org.gtk.example", G_APPLICATION_DEFAULT_FLAGS);
  g_signal_connect (app, "activate", G_CALLBACK (activate), NULL);
  status = g_application_run (G_APPLICATION (app), argc, argv);
  g_object_unref (app);

  return status;
}
2

Hi,

It’s not possible, dropdown are designed around single-selections only, as they display the selected item in their button.
Technically, Gtk.DropDown automatically creates a Gtk.SingleSelection to wrap the provided model, so that will override your multi-selection.

You may want to use other widgets instead:

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