columnview: Revise the constructor

Make gtk_column_view_new take a model as first argument,
and make it allow-none and transfer full.

Update all callers.

gtk/gtkcolumnview.c

@@ -1179,19 +1179,30 @@ gtk_column_view_init (GtkColumnView *self)
 
 /**
  * gtk_column_view_new:
+ * @model: (allow-none) (transfer full): the list model to use, or %NULL
  *
- * Creates a new empty #GtkColumnView.
+ * Creates a new #GtkColumnView.
  *
- * You most likely want to call gtk_column_view_set_factory() to
- * set up a way to map its items to widgets and gtk_column_view_set_model()
- * to set a model to provide items next.
+ * You most likely want to call gtk_column_view_append_column() to
+ * add columns next.
  *
  * Returns: a new #GtkColumnView
  **/
 GtkWidget *
-gtk_column_view_new (void)
+gtk_column_view_new (GListModel *model)
 {
-  return g_object_new (GTK_TYPE_COLUMN_VIEW, NULL);
+  GtkWidget *result;
+
+  g_return_val_if_fail (model == NULL || G_IS_LIST_MODEL (model), NULL);
+
+  result = g_object_new (GTK_TYPE_COLUMN_VIEW,
+                         "model", model,
+                         NULL);
+
+  /* consume the reference */
+  g_clear_object (&model);
+
+  return result;
 }
 
 /**

gtk/gtkcolumnview.h

@@ -51,7 +51,7 @@ GDK_AVAILABLE_IN_ALL
 GType           gtk_column_view_get_type                        (void) G_GNUC_CONST;
 
 GDK_AVAILABLE_IN_ALL
-GtkWidget *     gtk_column_view_new                             (void);
+GtkWidget *     gtk_column_view_new                             (GListModel             *model);
 
 GDK_AVAILABLE_IN_ALL
 GListModel *    gtk_column_view_get_columns                     (GtkColumnView          *self);

tests/testlistdnd.c

@@ -381,11 +381,7 @@ main (int argc, char *argv[])
   gtk_scrolled_window_set_has_frame (GTK_SCROLLED_WINDOW (sw), TRUE);
   gtk_stack_add_titled (GTK_STACK (stack), sw, "column", "GtkColumnView");
 
-  cv = gtk_column_view_new ();
-
-  model = create_model (0, 400, 1, FALSE);
-  gtk_column_view_set_model (GTK_COLUMN_VIEW (cv), model);
-  g_object_unref (model);
+  cv = gtk_column_view_new (create_model (0, 400, 1, FALSE));
 
   for (guint i = 0; i < 20; i++)
     {