[gtkmm] Slight whitespace change.

[Murray Cumming <murrayc src gnome org>]

commit a5dfef6fc2a163e473000eca97ccdab597b6c00a
Author: Murray Cumming <murrayc murrayc com>
Date:   Thu Apr 14 15:34:34 2016 +0200

    Slight whitespace change.

 gtk/src/treeview.hg |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/gtk/src/treeview.hg b/gtk/src/treeview.hg
index 75dd0e6..b795e54 100644
--- a/gtk/src/treeview.hg
+++ b/gtk/src/treeview.hg
@@ -1189,7 +1189,8 @@ void _auto_store_on_cellrenderer_text_edited_numerical(const Glib::ustring& path
       try
       {
         new_value =  static_cast<ColumnType>( std::stod(new_text) );
-      } catch(const std::invalid_argument&)
+      }
+      catch(const std::invalid_argument&)
       {
          //Intentionally ignored.
          //Applications can use their own logic if they want to handle invalid input differently.