[LyX/master] Add forgotten initialization

[Juergen Spitzmueller]

commit 44a0748ba3958c1713bd4239340a256ef58f145f
Author: Juergen Spitzmueller <sp...@lyx.org>
Date:   Thu Dec 20 13:46:41 2018 +0100

    Add forgotten initialization
---
 src/frontends/qt4/ButtonController.cpp |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/src/frontends/qt4/ButtonController.cpp 
b/src/frontends/qt4/ButtonController.cpp
index 25dcee7..c8644ab 100644
--- a/src/frontends/qt4/ButtonController.cpp
+++ b/src/frontends/qt4/ButtonController.cpp
@@ -93,7 +93,7 @@ public:
        typedef QList<CheckedLineEdit> CheckedWidgetList;
 
        Private()
-               : okay_(0), apply_(0), cancel_(0), restore_(0), auto_apply_(0),
+               : okay_(0), apply_(0), cancel_(0), restore_(0), auto_apply_(0), 
default_(0),
                        policy_(ButtonPolicy::IgnorantPolicy)
        {}