diff -urp overlay-scrollbar_default-r379.orig/os/os-bar.c overlay-scrollbar_default-r379/os/os-bar.c
--- overlay-scrollbar_default-r379.orig/os/os-bar.c	2013-10-03 00:04:49.000000000 +0200
+++ overlay-scrollbar_default-r379/os/os-bar.c	2013-10-03 00:34:14.187729456 +0200
@@ -480,8 +480,10 @@ os_bar_connect (OsBar       *bar,
  * @bar: a #OsBar
  *
  * Hides the #OsBar.
+ *
+ * Returns: FALSE.
  **/
-void
+gboolean
 os_bar_hide (OsBar *bar)
 {
   OsBarPrivate *priv;
@@ -493,7 +495,7 @@ os_bar_hide (OsBar *bar)
   priv->visible = FALSE;
 
   if (priv->parent == NULL)
-    return;
+    return FALSE;
 
   /* Immediately hide, then stop animations. */
   gdk_window_hide (priv->tail_window);
@@ -501,6 +503,7 @@ os_bar_hide (OsBar *bar)
 
   os_animation_stop (priv->tail_animation, retract_tail_stop_cb);
   os_animation_stop (priv->state_animation, change_state_stop_cb);
+  return FALSE;
 }
 
 /* Move a mask on the bar_window, fake movement. */
@@ -814,8 +817,10 @@ os_bar_set_parent (OsBar     *bar,
  * @bar: a #OsBar
  *
  * Shows @bar.
+ *
+ * Returns: FALSE.
  **/
-void
+gboolean
 os_bar_show (OsBar *bar)
 {
   OsBarPrivate *priv;
@@ -827,9 +832,10 @@ os_bar_show (OsBar *bar)
   priv->visible = TRUE;
 
   if (priv->parent == NULL)
-    return;
+    return FALSE;
 
   gdk_window_show (priv->bar_window);
+  return FALSE;
 }
 
 /**
diff -urp overlay-scrollbar_default-r379.orig/os/os-private.h overlay-scrollbar_default-r379/os/os-private.h
--- overlay-scrollbar_default-r379.orig/os/os-private.h	2013-10-03 00:04:49.000000000 +0200
+++ overlay-scrollbar_default-r379/os/os-private.h	2013-10-03 00:15:55.379683902 +0200
@@ -188,7 +188,7 @@ GType  os_bar_get_type      (void) G_GNU
 
 OsBar* os_bar_new           (void);
 
-void   os_bar_hide          (OsBar *bar);
+gboolean os_bar_hide          (OsBar *bar);
 
 void   os_bar_connect       (OsBar       *bar,
                              GdkRectangle mask);
@@ -207,7 +207,7 @@ void   os_bar_set_detached  (OsBar   *ba
 void   os_bar_set_parent    (OsBar     *bar,
                              GtkWidget *parent);
 
-void   os_bar_show          (OsBar *bar);
+gboolean os_bar_show          (OsBar *bar);
 
 void   os_bar_size_allocate (OsBar       *bar,
                              GdkRectangle rectangle);
diff -urp overlay-scrollbar_default-r379.orig/os/os-scrollbar.c overlay-scrollbar_default-r379/os/os-scrollbar.c
--- overlay-scrollbar_default-r379.orig/os/os-scrollbar.c	2013-10-03 00:04:49.000000000 +0200
+++ overlay-scrollbar_default-r379/os/os-scrollbar.c	2013-10-03 00:41:10.567746718 +0200
@@ -2528,7 +2528,6 @@ thumb_unmap_cb (GtkWidget *widget,
 
   priv->event = OS_EVENT_NONE;
   priv->hidable_thumb = TRUE;
-  priv->state &= OS_STATE_FULLSIZE;
 
   /* Remove running hide timeout, if there is one. */
   if (priv->source_hide_thumb_id != 0)
@@ -3467,8 +3466,17 @@ hijacked_scrollbar_map (GtkWidget *widge
         }
 #endif
 
-      if (!(priv->state & OS_STATE_FULLSIZE))
-        os_bar_show (priv->bar);
+      if (gtk_adjustment_get_upper (priv->adjustment) - gtk_adjustment_get_lower (priv->adjustment) >
+          gtk_adjustment_get_page_size (priv->adjustment))
+        {
+          priv->state &= ~(OS_STATE_FULLSIZE);
+          g_idle_add((GSourceFunc) &os_bar_show, (gpointer) priv->bar);
+        }
+      else
+        {
+          priv->state |= OS_STATE_FULLSIZE;
+          g_idle_add((GSourceFunc) &os_bar_hide, (gpointer) priv->bar);
+        }
 
       if (!is_insensitive (scrollbar))
         {