[gtk/subpop/docs-getting-started-hello-world] Update docs/reference/gtk/getting_started.md

[Link Dupont <link src gnome org>]

commit 349f71ee2ffb1186b21cf7c21dd44619f6210f88
Author: Link Dupont <link sub-pop net>
Date:   Wed Oct 20 02:36:12 2021 +0000

    Update docs/reference/gtk/getting_started.md

 docs/reference/gtk/getting_started.md | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)
---
diff --git a/docs/reference/gtk/getting_started.md b/docs/reference/gtk/getting_started.md
index e1d3f2c8f2..761367a952 100644
--- a/docs/reference/gtk/getting_started.md
+++ b/docs/reference/gtk/getting_started.md
@@ -161,19 +161,24 @@ activate (GtkApplication *app,
 {
   GtkWidget *window;
   GtkWidget *button;
+  GtkWidget *box;
 
   window = gtk_application_window_new (app);
   gtk_window_set_title (GTK_WINDOW (window), "Window");
   gtk_window_set_default_size (GTK_WINDOW (window), 200, 200);
 
+  box = gtk_box_new (GTK_ORIENTATION_VERTICAL, 0);
+  gtk_widget_set_halign (box, GTK_ALIGN_CENTER);
+  gtk_widget_set_valign (box, GTK_ALIGN_CENTER);
+  
+  gtk_window_set_child (GTK_WINDOW (window), box);
+
   button = gtk_button_new_with_label ("Hello World");
-  gtk_widget_set_halign (button, GTK_ALIGN_CENTER);
-  gtk_widget_set_valign (button, GTK_ALIGN_CENTER);
 
   g_signal_connect (button, "clicked", G_CALLBACK (print_hello), NULL);
   g_signal_connect_swapped (button, "clicked", G_CALLBACK (gtk_window_destroy), window);
 
-  gtk_window_set_child (GTK_WINDOW (window), button);
+  gtk_box_append (GTK_BOX (box), button);
 
   gtk_widget_show (window);
 }