[gtk+] scale button: Add a style class

[Matthias Clasen <matthiasc src gnome org>]

commit 2c5e25a5c719e9b3375461adf3502e7fc2110b03
Author: Matthias Clasen <mclasen redhat com>
Date:   Fri Oct 30 00:51:13 2015 -0400

    scale button: Add a style class
    
    Add a .scale style class to differentiate scale buttons from normal
    ones.

 gtk/gtkscalebutton.c |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtkscalebutton.c b/gtk/gtkscalebutton.c
index f797399..010f926 100644
--- a/gtk/gtkscalebutton.c
+++ b/gtk/gtkscalebutton.c
@@ -65,6 +65,11 @@
  * This kind of widget is commonly used for volume controls in multimedia
  * applications, and GTK+ provides a #GtkVolumeButton subclass that
  * is tailored for this use case.
+ *
+ * # CSS nodes
+ *
+ * GtkScaleButton has a single CSS node with name button. To differentiate
+ * it from a plain #GtkButton, it gets the .scale style class.
  */
 
 
@@ -338,12 +343,14 @@ gtk_scale_button_class_init (GtkScaleButtonClass *klass)
   gtk_widget_class_bind_template_callback (widget_class, cb_popup_mapped);
 
   gtk_widget_class_set_accessible_type (widget_class, GTK_TYPE_SCALE_BUTTON_ACCESSIBLE);
+  gtk_widget_class_set_css_name (widget_class, "button");
 }
 
 static void
 gtk_scale_button_init (GtkScaleButton *button)
 {
   GtkScaleButtonPrivate *priv;
+  GtkStyleContext *context;
 
   button->priv = priv = gtk_scale_button_get_instance_private (button);
 
@@ -358,6 +365,9 @@ gtk_scale_button_init (GtkScaleButton *button)
   g_object_ref (priv->adjustment);
 
   gtk_widget_add_events (GTK_WIDGET (button), GDK_SMOOTH_SCROLL_MASK);
+
+  context = gtk_widget_get_style_context (GTK_WIDGET (button));
+  gtk_style_context_add_class (context, "scale");
 }
 
 static void