[LyX/master] Update previews on preference change (#9507)

[Scott Kostyshak]

commit 390ae05444cf4899a3028dcbbfe1095ecd2d207a
Author: Scott Kostyshak <skost...@lyx.org>
Date:   Sun Apr 19 02:30:28 2015 -0400

    Update previews on preference change (#9507)
    
    Normally the theBufferList().updatePreviews(); statement would go inside
    of PrefDisplay::applyRC. However, that would not work well because
    Buffer::updatePreviews() calls loader() which conditions on
    (lyxrc.preview == LyXRC::PREVIEW_OFF) but the new RC has not been set at
    this point.

diff --git a/src/BufferList.cpp b/src/BufferList.cpp
index c253282..68a1e80 100644
--- a/src/BufferList.cpp
+++ b/src/BufferList.cpp
@@ -344,6 +344,15 @@ void BufferList::recordCurrentAuthor(Author const & author)
 }
 
 
+void BufferList::updatePreviews()
+{
+       BufferStorage::iterator it = bstore.begin();
+       BufferStorage::iterator end = bstore.end();
+       for (; it != end; ++it)
+               (*it)->updatePreviews();
+}
+
+
 int BufferList::bufferNum(FileName const & fname) const
 {
        FileNameList const buffers(fileNames());
diff --git a/src/BufferList.h b/src/BufferList.h
index 4f9cb95..242eff0 100644
--- a/src/BufferList.h
+++ b/src/BufferList.h
@@ -115,6 +115,8 @@ public:
        //@{
        /// reset current author for all buffers
        void recordCurrentAuthor(Author const & author);
+       /// update previews for all buffers, e.g. for Prefs update
+       void updatePreviews();
        /// Call changed() on all buffers, internal or not
        void changed(bool update_metrics) const;
        /// emergency save for all buffers
diff --git a/src/frontends/qt4/GuiPrefs.cpp b/src/frontends/qt4/GuiPrefs.cpp
index df0675a..9b6025e 100644
--- a/src/frontends/qt4/GuiPrefs.cpp
+++ b/src/frontends/qt4/GuiPrefs.cpp
@@ -3456,6 +3456,8 @@ void GuiPreferences::dispatchParams()
                update_screen_font_ = false;
        }
 
+       theBufferList().updatePreviews();
+
        // The Save button has been pressed
        if (isClosing())
                dispatch(FuncRequest(LFUN_PREFERENCES_SAVE));