[gnome-calculator] Fix uninitialised variable

[Robert Ancell <rancell src gnome org>]

commit 51635adf93e01b694688d56c3c2c88cf7bafd8fe
Author: Robert Ancell <robert ancell canonical com>
Date:   Mon Apr 15 09:26:39 2013 +1200

    Fix uninitialised variable

 src/math-buttons.vala | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/src/math-buttons.vala b/src/math-buttons.vala
index beb0405..f75533a 100644
--- a/src/math-buttons.vala
+++ b/src/math-buttons.vala
@@ -707,6 +707,7 @@ public class MathButtons : Gtk.Box
         button.get_allocation (out allocation);
         x = (int) (origin_x + allocation.x + border);
         y = (int) (origin_y + allocation.y + border);
+        push_in = false;
     }
 
     private void memory_cb (Gtk.Widget widget)