[gtk+/gtk-style-context] GtkWidget: unset NULL properties when overriding style.

[Carlos Garnacho <carlosg src gnome org>]

commit 7313a3dc25185cc6b6ee0e4ba6ed55a850d0475f
Author: Carlos Garnacho <carlosg gnome org>
Date:   Mon Nov 29 11:27:43 2010 +0100

    GtkWidget: unset NULL properties when overriding style.

 gtk/gtkwidget.c |   29 ++++++++++++++++++++---------
 1 files changed, 20 insertions(+), 9 deletions(-)
---
diff --git a/gtk/gtkwidget.c b/gtk/gtkwidget.c
index 7ab4a9c..58f6995 100644
--- a/gtk/gtkwidget.c
+++ b/gtk/gtkwidget.c
@@ -8032,9 +8032,12 @@ gtk_widget_override_color (GtkWidget     *widget,
 
   properties = _gtk_widget_get_modifier_properties (widget);
 
-  gtk_style_properties_set (properties, state,
-                            "color", color,
-                            NULL);
+  if (color)
+    gtk_style_properties_set (properties, state,
+                              "color", color,
+                              NULL);
+  else
+    gtk_style_properties_unset_property (properties, "color", state);
 
   context = gtk_widget_get_style_context (widget);
   gtk_style_context_invalidate (context);
@@ -8069,9 +8072,14 @@ gtk_widget_override_background_color (GtkWidget     *widget,
 
   properties = _gtk_widget_get_modifier_properties (widget);
 
-  gtk_style_properties_set (properties, state,
-                            "background-color", color,
-                            NULL);
+  if (color)
+    gtk_style_properties_set (properties, state,
+                              "background-color", color,
+                              NULL);
+  else
+    gtk_style_properties_unset_property (properties,
+                                         "background-color",
+                                         state);
 
   context = gtk_widget_get_style_context (widget);
   gtk_style_context_invalidate (context);
@@ -8105,9 +8113,12 @@ gtk_widget_override_font (GtkWidget                  *widget,
 
   properties = _gtk_widget_get_modifier_properties (widget);
 
-  gtk_style_properties_set (properties, 0,
-                            "font", font_desc,
-                            NULL);
+  if (font_desc)
+    gtk_style_properties_set (properties, 0,
+                              "font", font_desc,
+                              NULL);
+  else
+    gtk_style_properties_unset_property (properties, "font", 0);
 
   context = gtk_widget_get_style_context (widget);
   gtk_style_context_invalidate (context);