[gtk] headerbar: Fix fallback appmenu

[Matthias Clasen <matthiasc src gnome org>]

commit f1fe54f337453fa58b081690368d5931b5b777a0
Author: Matthias Clasen <mclasen redhat com>
Date:   Thu Jun 13 19:31:48 2019 +0000

    headerbar: Fix fallback appmenu
    
    We were using menubuttons here in a way that
    does not work anymore. Make it work again.

 gtk/gtkheaderbar.c             |  3 ++-
 gtk/gtkmenubutton.c            | 14 ++++++++++++++
 gtk/gtkmenubuttonprivate.h     |  3 +++
 gtk/theme/Adwaita/_common.scss | 10 +++++++++-
 4 files changed, 28 insertions(+), 2 deletions(-)
---
diff --git a/gtk/gtkheaderbar.c b/gtk/gtkheaderbar.c
index 41bc434189..35553835a8 100644
--- a/gtk/gtkheaderbar.c
+++ b/gtk/gtkheaderbar.c
@@ -37,6 +37,7 @@
 #include "gtkwidgetprivate.h"
 #include "gtkwindowprivate.h"
 #include "gtknative.h"
+#include "gtkmenubuttonprivate.h"
 
 #include "a11y/gtkcontaineraccessible.h"
 
@@ -388,7 +389,7 @@ _gtk_header_bar_update_window_buttons (GtkHeaderBar *bar)
                   gtk_style_context_add_class (gtk_widget_get_style_context (button), "titlebutton");
                   gtk_style_context_add_class (gtk_widget_get_style_context (button), "appmenu");
                   image = gtk_image_new ();
-                  gtk_container_add (GTK_CONTAINER (button), image);
+                  gtk_menu_button_add_child (GTK_MENU_BUTTON (button), image);
                   gtk_widget_set_can_focus (button, FALSE);
 
                   accessible = gtk_widget_get_accessible (button);
diff --git a/gtk/gtkmenubutton.c b/gtk/gtkmenubutton.c
index c4813ebbc7..f3a6742ae3 100644
--- a/gtk/gtkmenubutton.c
+++ b/gtk/gtkmenubutton.c
@@ -1434,3 +1434,17 @@ gtk_menu_button_popdown (GtkMenuButton *menu_button)
 
   gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (priv->button), FALSE);
 }
+
+void
+gtk_menu_button_add_child (GtkMenuButton *menu_button,
+                           GtkWidget     *new_child)
+{
+  GtkMenuButtonPrivate *priv = gtk_menu_button_get_instance_private (menu_button);
+  GtkWidget *child;
+
+  child = gtk_bin_get_child (GTK_BIN (priv->button));
+  if (child)
+    gtk_container_remove (GTK_CONTAINER (priv->button), child);
+
+  gtk_container_add (GTK_CONTAINER (priv->button), new_child);
+}
diff --git a/gtk/gtkmenubuttonprivate.h b/gtk/gtkmenubuttonprivate.h
index 982ad2bdf9..85114c3318 100644
--- a/gtk/gtkmenubuttonprivate.h
+++ b/gtk/gtkmenubuttonprivate.h
@@ -32,6 +32,9 @@ void       _gtk_menu_button_set_popup_with_func (GtkMenuButton                 *
                                                  GtkMenuButtonShowMenuCallback  func,
                                                  gpointer                       user_data);
 
+void   gtk_menu_button_add_child (GtkMenuButton *button,
+                                  GtkWidget     *child);
+
 G_END_DECLS
 
 #endif /* __GTK_MENU_BUTTON_PRIVATE_H__ */
diff --git a/gtk/theme/Adwaita/_common.scss b/gtk/theme/Adwaita/_common.scss
index 8bb956bd05..86b7d3e92a 100644
--- a/gtk/theme/Adwaita/_common.scss
+++ b/gtk/theme/Adwaita/_common.scss
@@ -1657,12 +1657,20 @@ headerbar {
     min-height: 28px;
     padding: 4px;
 
-    button.titlebutton {
+    button.titlebutton,
+    menubutton.titlebutton {
       min-height: 26px;
       min-width: 26px;
       margin: 0;
       padding: 0;
     }
+
+    menubutton.titlebutton button {
+      min-height: 20px;
+      min-width: 20px;
+      margin: 0;
+      padding: 4px;
+    }
   }
 
   separator.titlebutton { opacity: 0; } /* hide the close button separator */