[gtk+] GtkStyleContext is meant to have a GdkScreen

[Carlos Garnacho <carlosg src gnome org>]

commit 217d3fd796c29c01dac9420b5ff599d2a55d9d73
Author: Carlos Garnacho <carlosg gnome org>
Date:   Sun Feb 6 02:40:06 2011 +0100

    GtkStyleContext is meant to have a GdkScreen
    
    It is used to get the default providers, without them
    the style context can't do much. A check for NULL screen
    is done before any sensitive call to
    gtk_style_context_set_screen(), in the hope that any widget
    will open the display before doing anything related to
    styling. Fixes bug #641429, reported by Bastien Nocera.

 gtk/gtkstyle.c        |    1 +
 gtk/gtkstylecontext.c |    2 +-
 gtk/gtkwidget.c       |   16 ++++++++++++----
 3 files changed, 14 insertions(+), 5 deletions(-)
---
diff --git a/gtk/gtkstyle.c b/gtk/gtkstyle.c
index 5347119..1d31d1e 100644
--- a/gtk/gtkstyle.c
+++ b/gtk/gtkstyle.c
@@ -822,6 +822,7 @@ _gtk_style_new_for_path (GdkScreen     *screen,
 
   if (screen)
     gtk_style_context_set_screen (context, screen);
+
   gtk_style_context_set_path (context, path);
 
   style = g_object_new (GTK_TYPE_STYLE,
diff --git a/gtk/gtkstylecontext.c b/gtk/gtkstylecontext.c
index 6eed378..7cd0dab 100644
--- a/gtk/gtkstylecontext.c
+++ b/gtk/gtkstylecontext.c
@@ -2617,7 +2617,7 @@ gtk_style_context_set_screen (GtkStyleContext *context,
   GtkStyleContextPrivate *priv;
 
   g_return_if_fail (GTK_IS_STYLE_CONTEXT (context));
-  g_return_if_fail (screen == NULL || GDK_IS_SCREEN (screen));
+  g_return_if_fail (GDK_IS_SCREEN (screen));
 
   priv = context->priv;
   if (priv->screen == screen)
diff --git a/gtk/gtkwidget.c b/gtk/gtkwidget.c
index 74d83f2..bea97d8 100644
--- a/gtk/gtkwidget.c
+++ b/gtk/gtkwidget.c
@@ -7738,11 +7738,15 @@ gtk_widget_set_parent (GtkWidget *widget,
 
   if (widget->priv->context)
     {
+      GdkScreen *screen;
+
       _gtk_widget_update_path (widget);
       gtk_style_context_set_path (widget->priv->context, widget->priv->path);
 
-      gtk_style_context_set_screen (widget->priv->context,
-                                    gtk_widget_get_screen (widget));
+      screen = gtk_widget_get_screen (widget);
+
+      if (screen)
+        gtk_style_context_set_screen (widget->priv->context, screen);
     }
 
   gtk_widget_pop_verify_invariants (widget);
@@ -14171,6 +14175,8 @@ gtk_widget_get_style_context (GtkWidget *widget)
 
   if (G_UNLIKELY (!widget->priv->context))
     {
+      GdkScreen *screen;
+
       widget->priv->context = g_object_new (GTK_TYPE_STYLE_CONTEXT,
                                             "direction", gtk_widget_get_direction (widget),
                                             NULL);
@@ -14178,8 +14184,10 @@ gtk_widget_get_style_context (GtkWidget *widget)
       g_signal_connect (widget->priv->context, "changed",
                         G_CALLBACK (style_context_changed), widget);
 
-      gtk_style_context_set_screen (widget->priv->context,
-                                    gtk_widget_get_screen (widget));
+      screen = gtk_widget_get_screen (widget);
+
+      if (screen)
+        gtk_style_context_set_screen (widget->priv->context, screen);
 
       _gtk_widget_update_path (widget);
       gtk_style_context_set_path (widget->priv->context,