[gnome-control-center] display: Ensure we generate the UI initially on two output mode

[Rui Matos <rtcm src gnome org>]

commit 337802315ce91572d9de69c36e3f32e48e252fef
Author: Rui Matos <tiagomatos gmail com>
Date:   Fri Aug 25 16:44:50 2017 +0200

    display: Ensure we generate the UI initially on two output mode
    
    We rely on visible-child-name notifications to generate the
    appropriate UI, unfortunately it doesn't happen for the first added
    stack page if the widget is already visible. Work around this by
    adding a dummy page first.

 panels/display/cc-display-panel.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/panels/display/cc-display-panel.c b/panels/display/cc-display-panel.c
index 4101899..0940e18 100644
--- a/panels/display/cc-display-panel.c
+++ b/panels/display/cc-display-panel.c
@@ -2016,6 +2016,9 @@ make_two_output_ui (CcDisplayPanel *panel)
 
   stack = gtk_stack_new ();
   gtk_container_add (GTK_CONTAINER (vbox), stack);
+  /* Add a dummy first stack page so that setting the visible child
+   * below triggers a visible-child-name notification. */
+  gtk_stack_add_named (GTK_STACK (stack), make_bin (), "dummy");
 
   add_two_output_page (switcher, stack, "join", _("Join Displays"),
                        "video-joined-displays-symbolic");