[gtk+] GtkStyleContext: Avoid over-eager animation cancellation

[Matthias Clasen <matthiasc src gnome org>]

commit 9f008e347788da4799c5c12729a94c25cb6f07fb
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Jun 29 19:33:46 2014 -0400

    GtkStyleContext: Avoid over-eager animation cancellation
    
    When validating the style context, we are copying the animations
    from one StyleValues instance to another, and cancel the old ones.
    It turns out that sometimes the old and the new StyleValues are
    the same, and in this case, we end up cancelling the animations
    for good.
    
    One case where breakage from this was observed is that the spinners
    in gtk3-widget-factory stop spinning when you open and close a modal
    dialog on page 2. This depends a bit on the window manager; the problem
    can only be seen if opening the dialog causes a transition to backdrop.

 gtk/gtkstylecontext.c |   16 +++++++++-------
 1 files changed, 9 insertions(+), 7 deletions(-)
---
diff --git a/gtk/gtkstylecontext.c b/gtk/gtkstylecontext.c
index 1ca31bc..fd804b2 100644
--- a/gtk/gtkstylecontext.c
+++ b/gtk/gtkstylecontext.c
@@ -3058,12 +3058,13 @@ _gtk_style_context_validate (GtkStyleContext  *context,
 
       values = style_values_lookup (context);
 
-      _gtk_css_computed_values_create_animations (values,
-                                                  priv->parent ? style_values_lookup (priv->parent) : NULL,
-                                                  timestamp,
-                                                  GTK_STYLE_PROVIDER_PRIVATE (priv->cascade),
-                                                 priv->scale,
-                                                  gtk_style_context_should_create_transitions (context) ? 
current : NULL);
+      if (values != current)
+        _gtk_css_computed_values_create_animations (values,
+                                                    priv->parent ? style_values_lookup (priv->parent) : NULL,
+                                                    timestamp,
+                                                    GTK_STYLE_PROVIDER_PRIVATE (priv->cascade),
+                                                    priv->scale,
+                                                    gtk_style_context_should_create_transitions (context) ? 
current : NULL);
       if (_gtk_css_computed_values_is_static (values))
         change &= ~GTK_CSS_CHANGE_ANIMATE;
       else
@@ -3075,7 +3076,8 @@ _gtk_style_context_validate (GtkStyleContext  *context,
           changes = _gtk_css_computed_values_get_difference (values, current);
 
           /* In the case where we keep the cache, we want unanimated values */
-          _gtk_css_computed_values_cancel_animations (current);
+          if (values != current)
+            _gtk_css_computed_values_cancel_animations (current);
         }
       else
         {