[gtk+] scrolledwindow: Resolve whether we use overlay scrollbars early.

[Tristan Van Berkom <tvb src gnome org>]

commit 34feba1e7c5c86164592588bde479c97a5b96160
Author: Tristan Van Berkom <tristan vanberkom codethink co uk>
Date:   Tue Jun 7 14:09:28 2016 +0900

    scrolledwindow: Resolve whether we use overlay scrollbars early.
    
    Widgets should support size requests before being realized in general,
    otherwise this can cause flicker/resize at initial display time as
    the toplevel window can make a request before realize/allocate.
    
    This also makes the added testsuite/gtk/scrolledwindow.c test work again,
    this was broken because we only ever calculate whether we are going
    to use overlay scrollbars once the scrolled window is realized (and
    the test case does not realize any window).

 gtk/gtkscrolledwindow.c |   37 ++++++++++++++++++++++++-------------
 1 files changed, 24 insertions(+), 13 deletions(-)
---
diff --git a/gtk/gtkscrolledwindow.c b/gtk/gtkscrolledwindow.c
index a3a89b6..7d149ae 100644
--- a/gtk/gtkscrolledwindow.c
+++ b/gtk/gtkscrolledwindow.c
@@ -400,6 +400,7 @@ static gboolean _gtk_scrolled_window_get_overshoot (GtkScrolledWindow *scrolled_
 static void     gtk_scrolled_window_start_deceleration (GtkScrolledWindow *scrolled_window);
 static gint     _gtk_scrolled_window_get_scrollbar_spacing (GtkScrolledWindow *scrolled_window);
 
+static void     gtk_scrolled_window_update_use_indicators (GtkScrolledWindow *scrolled_window);
 static void     remove_indicator     (GtkScrolledWindow *sw,
                                       Indicator         *indicator);
 static void     indicator_stop_fade  (Indicator         *indicator);
@@ -2146,6 +2147,8 @@ gtk_scrolled_window_init (GtkScrolledWindow *scrolled_window)
       gtk_css_node_set_state (priv->undershoot_node[i], gtk_css_node_get_state (widget_node));
       g_object_unref (priv->undershoot_node[i]);
     }
+
+  gtk_scrolled_window_update_use_indicators (scrolled_window);
 }
 
 /**
@@ -4317,6 +4320,23 @@ remove_indicator (GtkScrolledWindow *scrolled_window,
 }
 
 static void
+gtk_scrolled_window_sync_use_indicators (GtkScrolledWindow *scrolled_window)
+{
+  GtkScrolledWindowPrivate *priv = scrolled_window->priv;
+
+  if (priv->use_indicators)
+    {
+      setup_indicator (scrolled_window, &priv->hindicator, priv->hscrollbar);
+      setup_indicator (scrolled_window, &priv->vindicator, priv->vscrollbar);
+    }
+  else
+    {
+      remove_indicator (scrolled_window, &priv->hindicator);
+      remove_indicator (scrolled_window, &priv->vindicator);
+    }
+}
+
+static void
 gtk_scrolled_window_update_use_indicators (GtkScrolledWindow *scrolled_window)
 {
   GtkScrolledWindowPrivate *priv = scrolled_window->priv;
@@ -4331,16 +4351,8 @@ gtk_scrolled_window_update_use_indicators (GtkScrolledWindow *scrolled_window)
     {
       priv->use_indicators = use_indicators;
 
-      if (priv->use_indicators)
-        {
-          setup_indicator (scrolled_window, &priv->hindicator, priv->hscrollbar);
-          setup_indicator (scrolled_window, &priv->vindicator, priv->vscrollbar);
-        }
-      else
-        {
-          remove_indicator (scrolled_window, &priv->hindicator);
-          remove_indicator (scrolled_window, &priv->vindicator);
-        }
+      if (gtk_widget_get_realized (GTK_WIDGET (scrolled_window)))
+        gtk_scrolled_window_sync_use_indicators (scrolled_window);
 
       gtk_widget_queue_resize (GTK_WIDGET (scrolled_window));
     }
@@ -4383,7 +4395,7 @@ gtk_scrolled_window_realize (GtkWidget *widget)
   priv->hindicator.scrollbar = priv->hscrollbar;
   priv->vindicator.scrollbar = priv->vscrollbar;
 
-  gtk_scrolled_window_update_use_indicators (scrolled_window);
+  gtk_scrolled_window_sync_use_indicators (scrolled_window);
 }
 
 static void
@@ -4587,8 +4599,7 @@ gtk_scrolled_window_set_overlay_scrolling (GtkScrolledWindow *scrolled_window,
     {
       priv->overlay_scrolling = overlay_scrolling;
 
-      if (gtk_widget_get_realized (GTK_WIDGET (scrolled_window)))
-        gtk_scrolled_window_update_use_indicators (scrolled_window);
+      gtk_scrolled_window_update_use_indicators (scrolled_window);
 
       g_object_notify_by_pspec (G_OBJECT (scrolled_window), properties[PROP_OVERLAY_SCROLLING]);
     }