[dconf-editor] Add an unused signal.

[Arnaud B. <arnaudb src gnome org>]

commit 6f42a7af7ff39b60c2577f1eab22fbf03d425a69
Author: Arnaud Bonatti <arnaud bonatti gmail com>
Date:   Sun Aug 4 12:32:44 2019 +0200

    Add an unused signal.
    
    Sync a bit with Taquin.

 editor/adaptative-window.vala | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)
---
diff --git a/editor/adaptative-window.vala b/editor/adaptative-window.vala
index 7f60d13..b33e679 100644
--- a/editor/adaptative-window.vala
+++ b/editor/adaptative-window.vala
@@ -412,6 +412,8 @@ private abstract class AdaptativeWindow : ApplicationWindow
     * * manage high-constrast
     \*/
 
+    internal signal void gtk_theme_changed ();
+
     private void manage_high_contrast ()
     {
         Gtk.Settings? nullable_gtk_settings = Gtk.Settings.get_default ();
@@ -420,18 +422,19 @@ private abstract class AdaptativeWindow : ApplicationWindow
 
         Gtk.Settings gtk_settings = (!) nullable_gtk_settings;
         gtk_settings.notify ["gtk-theme-name"].connect (update_highcontrast_state);
-        _update_highcontrast_state (gtk_settings);
+        _update_highcontrast_state (gtk_settings.gtk_theme_name);
     }
 
     private void update_highcontrast_state (Object gtk_settings, ParamSpec unused)
     {
-        _update_highcontrast_state ((Gtk.Settings) gtk_settings);
+        _update_highcontrast_state (((Gtk.Settings) gtk_settings).gtk_theme_name);
+        gtk_theme_changed ();
     }
 
     private bool highcontrast_state = false;
-    private void _update_highcontrast_state (Gtk.Settings gtk_settings)
+    private void _update_highcontrast_state (string theme_name)
     {
-        bool highcontrast_new_state = "HighContrast" in gtk_settings.gtk_theme_name;
+        bool highcontrast_new_state = "HighContrast" in theme_name;
         if (highcontrast_new_state == highcontrast_state)
             return;
         highcontrast_state = highcontrast_new_state;