Add gtk_widget_add_tick_callback(), remove GtkTimeline, etc.

Add a very simple GtkWidget function for an "tick" callback, which
is connected to the ::update signal of GdkFrameClock.

Remove:

 - GtkTimeline. The consensus is that it is too complex.
 - GdkPaintClockTarget. In the rare cases where tick callbacks
    aren't sufficient, it's possible to track the
    paint clock with ::realize/::unrealize/::hierarchy-changed.

GtkTimeline is kept using ::update directly to allow using a GtkTimeline
with a paint clock but no widget.

1 files changed, 7 insertions, 0 deletions

diff --git a/gtk/gtkstylecontext.h b/gtk/gtkstylecontext.h
index dab758a5fb..35655f28d6 100644
--- a/gtk/gtkstylecontext.h
+++ b/gtk/gtkstylecontext.h
@@ -836,6 +836,13 @@ void        gtk_style_context_set_screen (GtkStyleContext *context,
                                           GdkScreen       *screen);
 GdkScreen * gtk_style_context_get_screen (GtkStyleContext *context);
 
+GDK_AVAILABLE_IN_3_8
+void           gtk_style_context_set_frame_clock (GtkStyleContext *context,
+                                                  GdkFrameClock   *frame_clock);
+GDK_AVAILABLE_IN_3_8
+GdkFrameClock *gtk_style_context_get_frame_clock (GtkStyleContext *context);
+
+
 GDK_DEPRECATED_IN_3_8_FOR(gtk_style_context_set_state)
 void             gtk_style_context_set_direction (GtkStyleContext  *context,
                                                   GtkTextDirection  direction);