[gnome-panel] libpanel-applet: use rgba visual if it is available

[Alberts Muktupāvels <muktupavels src gnome org>]

commit 9308cdff9aa8a0c4693e1ea2adf4c3756beb2046
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Sat Sep 5 18:16:28 2015 +0300

    libpanel-applet: use rgba visual if it is available
    
    https://bugzilla.gnome.org/show_bug.cgi?id=754306

 libpanel-applet/panel-applet.c |   18 ++++++++++++++++++
 1 files changed, 18 insertions(+), 0 deletions(-)
---
diff --git a/libpanel-applet/panel-applet.c b/libpanel-applet/panel-applet.c
index 4ca7ec9..f277517 100644
--- a/libpanel-applet/panel-applet.c
+++ b/libpanel-applet/panel-applet.c
@@ -1152,6 +1152,21 @@ panel_applet_button_release (GtkWidget      *widget,
        return panel_applet_button_event (applet, event);
 }
 
+static void
+panel_applet_composited_changed (GtkWidget *widget)
+{
+       GdkScreen *screen;
+       GdkVisual *visual;
+
+       screen = gtk_widget_get_screen (widget);
+       visual = gdk_screen_get_rgba_visual (screen);
+
+       if (visual == NULL)
+               visual = gdk_screen_get_system_visual (screen);
+
+       gtk_widget_set_visual (widget, visual);
+}
+
 static gboolean
 panel_applet_key_press_event (GtkWidget   *widget,
                              GdkEventKey *event)
@@ -1805,6 +1820,8 @@ panel_applet_init (PanelApplet *applet)
 
        context = gtk_widget_get_style_context (GTK_WIDGET (applet));
        gtk_style_context_add_class (context, GTK_STYLE_CLASS_HORIZONTAL);
+
+       panel_applet_composited_changed (GTK_WIDGET (applet));
 }
 
 static GObject *
@@ -1864,6 +1881,7 @@ panel_applet_class_init (PanelAppletClass *klass)
 
        widget_class->button_press_event = panel_applet_button_press;
        widget_class->button_release_event = panel_applet_button_release;
+       widget_class->composited_changed = panel_applet_composited_changed;
        widget_class->key_press_event = panel_applet_key_press_event;
        widget_class->get_request_mode = panel_applet_get_request_mode;
         widget_class->get_preferred_width = panel_applet_get_preferred_width;