Fix for "adjustment with non-zero page size" warning messages with
newer gtk+2

--- src/gData.ml.orig	Thu Sep 18 08:47:06 2014
+++ src/gData.ml	Thu Sep 18 11:24:43 2014
@@ -50,7 +50,7 @@ class adjustment obj = object (self)
 end
 
 let adjustment ?(value=0.) ?(lower=0.) ?(upper=100.)
-    ?(step_incr=1.) ?(page_incr=10.) ?(page_size=10.) () =
+    ?(step_incr=1.) ?(page_incr=10.) ?(page_size=0.) () =
   let w =
     Adjustment.create ~value ~lower ~upper ~step_incr ~page_incr ~page_size in
   new adjustment w