[gnome-software] Add global shortcuts for the back button

[Matthias Clasen <matthiasc src gnome org>]

commit b1e180b9c8467342f853f1b8bb1630404ad79e61
Author: Matthias Clasen <mclasen redhat com>
Date:   Fri Sep 20 17:14:02 2013 -0400

    Add global shortcuts for the back button
    
    Make both Back and Alt-Left (Alt-Right in rtl) activate the
    back button. Keyboard users love it.
    
    http://bugzilla.gnome.org/show_bug.cgi?id=708487

 src/gs-shell.c |   34 ++++++++++++++++++++++++++++++++++
 1 files changed, 34 insertions(+), 0 deletions(-)
---
diff --git a/src/gs-shell.c b/src/gs-shell.c
index ab88d38..d3b2586 100644
--- a/src/gs-shell.c
+++ b/src/gs-shell.c
@@ -365,6 +365,35 @@ text_changed_handler (GObject *entry, GParamSpec *pspec, GsShell *shell)
                gs_shell_change_mode (shell, GS_SHELL_MODE_OVERVIEW, NULL, NULL, TRUE);
 }
 
+static gboolean
+window_key_press_event (GtkWidget *win, GdkEventKey *event, GsShell *shell)
+{
+       GsShellPrivate *priv = shell->priv;
+       GdkKeymap *keymap;
+       GdkModifierType state;
+       gboolean is_rtl;
+       GtkWidget *button;
+
+       button = GTK_WIDGET (gtk_builder_get_object (priv->builder, "button_back"));
+       if (!gtk_widget_is_visible (button) || !gtk_widget_is_sensitive (button))
+               return GDK_EVENT_PROPAGATE;
+
+       state = event->state;
+       keymap = gdk_keymap_get_default ();
+       gdk_keymap_add_virtual_modifiers (keymap, &state);
+       state = state & gtk_accelerator_get_default_mod_mask ();
+       is_rtl = gtk_widget_get_direction (button) == GTK_TEXT_DIR_RTL;
+
+       if ((!is_rtl && state == GDK_MOD1_MASK && event->keyval == GDK_KEY_Left) ||
+           (is_rtl && state == GDK_MOD1_MASK && event->keyval == GDK_KEY_Right) ||
+           event->keyval == GDK_KEY_Back) {
+               gtk_widget_activate (button);
+               return GDK_EVENT_STOP;
+       }
+
+       return GDK_EVENT_PROPAGATE;
+}
+
 /**
  * gs_shell_setup:
  */
@@ -389,6 +418,7 @@ gs_shell_setup (GsShell *shell, GsPluginLoader *plugin_loader, GCancellable *can
 
        /* fix up the header bar */
        main_window = GTK_WIDGET (gtk_builder_get_object (priv->builder, "window_software"));
+
        widget = GTK_WIDGET (gtk_builder_get_object (priv->builder, "header"));
        g_object_ref (widget);
        gtk_container_remove (GTK_CONTAINER (gtk_widget_get_parent (widget)), widget);
@@ -402,6 +432,10 @@ gs_shell_setup (GsShell *shell, GsPluginLoader *plugin_loader, GCancellable *can
                gtk_image_set_from_icon_name (GTK_IMAGE (widget), "go-previous-rtl-symbolic", 
GTK_ICON_SIZE_MENU);
        }
 
+       /* global keynav */
+       g_signal_connect_after (main_window, "key_press_event",
+                               G_CALLBACK (window_key_press_event), shell);
+
        /* setup buttons */
        widget = GTK_WIDGET (gtk_builder_get_object (priv->builder, "button_back"));
        g_signal_connect (widget, "clicked",