[gnome-control-center] mouse: Don't use gtk_widget_show_all

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 1b24d7ca5f1473ea4e5cf9f8fca68112b568d9d8
Author: Robert Ancell <robert ancell canonical com>
Date:   Thu Oct 11 15:51:07 2018 +1300

    mouse: Don't use gtk_widget_show_all
    
    It is removed in GTK+ 4

 panels/mouse/test-gnome-mouse-test.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/panels/mouse/test-gnome-mouse-test.c b/panels/mouse/test-gnome-mouse-test.c
index c7d588bf9..557f36e0b 100644
--- a/panels/mouse/test-gnome-mouse-test.c
+++ b/panels/mouse/test-gnome-mouse-test.c
@@ -20,9 +20,10 @@ int main (int argc, char **argv)
   gtk_init (&argc, &argv);
 
   window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+  gtk_widget_show (window);
   widget = cc_mouse_test_new ();
+  gtk_widget_show (widget);
   gtk_container_add (GTK_CONTAINER (window), widget);
-  gtk_widget_show_all (window);
 
   g_signal_connect (G_OBJECT (window), "delete-event", G_CALLBACK (delete_event_cb), NULL);