[dconf-editor] Custom close-window button on small screen.

[Arnaud B. <arnaudb src gnome org>]

commit 8761704f35ee1590bac22c2337fad7a03ae9f67e
Author: Arnaud Bonatti <arnaud bonatti gmail com>
Date:   Thu Nov 22 13:09:42 2018 +0100

    Custom close-window button on small screen.

 editor/browser-headerbar.ui   | 19 +++++++++++++++++++
 editor/browser-headerbar.vala | 27 +++++++++++++++++++--------
 2 files changed, 38 insertions(+), 8 deletions(-)
---
diff --git a/editor/browser-headerbar.ui b/editor/browser-headerbar.ui
index ff76edd..96d3ff2 100644
--- a/editor/browser-headerbar.ui
+++ b/editor/browser-headerbar.ui
@@ -167,6 +167,25 @@
         </child>
       </object>
     </child>
+    <child>
+      <object class="GtkMenuButton" id="quit_button">
+        <property name="visible">False</property>
+        <property name="action-name">app.quit</property>
+        <style>
+          <class name="titlebutton"/>
+        </style>
+        <child>
+          <object class="GtkImage">
+            <property name="visible">True</property>
+            <property name="icon-name">window-close-symbolic</property>
+            <property name="icon-size">1</property>
+          </object>
+        </child>
+      </object>
+      <packing>
+        <property name="pack-type">end</property>
+      </packing>
+    </child>
     <child>
       <object class="GtkButton" id="show_modifications_button">
         <property name="visible">False</property>
diff --git a/editor/browser-headerbar.vala b/editor/browser-headerbar.vala
index c53f286..bb7dd7e 100644
--- a/editor/browser-headerbar.vala
+++ b/editor/browser-headerbar.vala
@@ -199,6 +199,7 @@ private class BrowserHeaderBar : HeaderBar, AdaptativeWidget
     [GtkChild] private Separator    modifications_separator;
     [GtkChild] private Button       show_modifications_button;
     [GtkChild] private Button       hide_modifications_button;
+    [GtkChild] private Button       quit_button;
     [GtkChild] private MenuButton   modifications_actions_button;
 
     bool in_window_modifications = false;
@@ -221,29 +222,39 @@ private class BrowserHeaderBar : HeaderBar, AdaptativeWidget
 
     private void update_modifications_button ()
     {
-        if (extra_small_window && delay_mode)
+        if (extra_small_window)
         {
             set_show_close_button (false);
             if (in_window_modifications)
             {
+                quit_button.hide ();
                 show_modifications_button.hide ();
                 modifications_separator.hide ();
             }
-            else if (in_window_bookmarks || in_window_about)
-            {
-                show_modifications_button.show ();
-                modifications_separator.hide ();
-            }
             else
             {
-                show_modifications_button.show ();
-                modifications_separator.show ();
+                if (delay_mode)
+                {
+                    quit_button.hide ();
+                    show_modifications_button.show ();
+                }
+                else
+                {
+                    show_modifications_button.hide ();
+                    quit_button.show ();
+                }
+
+                if (in_window_bookmarks || in_window_about)
+                    modifications_separator.hide ();
+                else
+                    modifications_separator.show ();
             }
         }
         else
         {
             if (in_window_modifications)
                 hide_in_window_modifications ();
+            quit_button.hide ();
             show_modifications_button.hide ();
             modifications_separator.hide ();
             set_show_close_button (true);