[gtk/matthiasc/for-master] listview: Add an example to the docs

[Matthias Clasen <matthiasc src gnome org>]

commit fe60972fe2c9cffa99329f29e0d9cc62e249af1c
Author: Matthias Clasen <mclasen redhat com>
Date:   Thu Jun 4 20:11:35 2020 -0400

    listview: Add an example to the docs
    
    The example is an excerpt from the applauncher
    demo in gtk4-demo.

 gtk/gtklistview.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)
---
diff --git a/gtk/gtklistview.c b/gtk/gtklistview.c
index beeef875b8..484f5b172c 100644
--- a/gtk/gtklistview.c
+++ b/gtk/gtklistview.c
@@ -62,6 +62,60 @@
  *
  * To learn more about the list widget framework, see the [overview](#ListWidget).
  *
+ * An example of using GtkListView:
+ * |[
+ * static void
+ * setup_listitem_cb (GtkListItemFactory *factory,
+ *                    GtkListItem        *list_item)
+ * {
+ *   GtkWidget *image;
+ *
+ *   image = gtk_image_new ();
+ *   gtk_image_set_icon_size (GTK_IMAGE (image), GTK_ICON_SIZE_LARGE);
+ *   gtk_list_item_set_child (list_item, image);
+ * }
+ *
+ * static void
+ * bind_listitem_cb (GtkListItemFactory *factory,
+ *                   GtkListItem        *list_item)
+ * {
+ *   GtkWidget *image;
+ *   GAppInfo *app_info;
+ *
+ *   image = gtk_list_item_get_child (list_item);
+ *   app_info = gtk_list_item_get_item (list_item);
+ *   gtk_image_set_from_gicon (GTK_IMAGE (image), g_app_info_get_icon (app_info));
+ * }
+ *
+ * static void
+ * activate_cb (GtkListView  *list,
+ *              guint         position,
+ *              gpointer      unused)
+ * {
+ *   GAppInfo *app_info;
+ *
+ *   app_info = g_list_model_get_item (gtk_list_view_get_model (list), position);
+ *   g_app_info_launch (app_info, NULL, NULL, NULL);
+ *   g_object_unref (app_info);
+ * }
+ *
+ * ...
+ *
+ *   factory = gtk_signal_list_item_factory_new ();
+ *   g_signal_connect (factory, "setup", G_CALLBACK (setup_listitem_cb), NULL);
+ *   g_signal_connect (factory, "bind", G_CALLBACK (bind_listitem_cb), NULL);
+ *
+ *   list = gtk_list_view_new_with_factory (factory);
+ *
+ *   g_signal_connect (list, "activate", G_CALLBACK (activate_cb), NULL);
+ *
+ *   model = create_application_list ();
+ *   gtk_list_view_set_model (GTK_LIST_VIEW (list), model);
+ *   g_object_unref (model);
+ *
+ *   gtk_scrolled_window_set_child (GTK_SCROLLED_WINDOW (sw), list);
+ * ]|
+ *
  * # CSS nodes
  *
  * |[<!-- language="plain" -->