[LyX/2.2.x] Work around dangling pointer

[Guillaume Munch]

commit adb00dbcf803298651609c0afac02bc4cb3db003
Author: Guillaume Munch <g...@lyx.org>
Date:   Wed Sep 28 21:57:54 2016 +0200

    Work around dangling pointer
    
    This pointer has been removed in master, but backporting the workaround is
    enough.
    
    (cherry picked from commit 79a947c9041a92805e9ac4b65594753410016fa5)
---
 src/frontends/qt4/GuiViewSource.cpp |    8 ++++----
 src/frontends/qt4/GuiViewSource.h   |    2 +-
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/frontends/qt4/GuiViewSource.cpp 
b/src/frontends/qt4/GuiViewSource.cpp
index 5a6a966..660da59 100644
--- a/src/frontends/qt4/GuiViewSource.cpp
+++ b/src/frontends/qt4/GuiViewSource.cpp
@@ -309,11 +309,11 @@ void ViewSourceWidget::realUpdateView()
 }
 
 
-docstring ViewSourceWidget::currentFormatName() const
+docstring ViewSourceWidget::currentFormatName(BufferView const * bv) const
 {
        // Compute the actual format used
-       string const format = !bv_ ? ""
-               : 
flavor2format(bv_->buffer().params().getOutputFlavor(view_format_));
+       string const format = !bv ? ""
+               : 
flavor2format(bv->buffer().params().getOutputFlavor(view_format_));
        Format const * f = formats.getFormat(format.empty() ? view_format_ : 
format);
        return from_utf8(f ? f->prettyname() : view_format_);
 }
@@ -453,7 +453,7 @@ bool GuiViewSource::initialiseParams(string const & 
/*source*/)
 
 void GuiViewSource::updateTitle()
 {
-       docstring const format = widget_->currentFormatName();
+       docstring const format = widget_->currentFormatName(bufferview());
        QString const title = format.empty() ? qt_("Code Preview")
                : qt_("%1[[preview format name]] Preview")
                  .arg(toqstr(translateIfPossible(format)));
diff --git a/src/frontends/qt4/GuiViewSource.h 
b/src/frontends/qt4/GuiViewSource.h
index b90c514..b7a5190 100644
--- a/src/frontends/qt4/GuiViewSource.h
+++ b/src/frontends/qt4/GuiViewSource.h
@@ -65,7 +65,7 @@ public Q_SLOTS:
        ///
        void gotoCursor();
        /// Name of the current format. Empty if none.
-       docstring currentFormatName() const;
+       docstring currentFormatName(BufferView const * bv) const;
 
 Q_SIGNALS:
        void formatChanged() const;