[LyX/master] Comment.

[Richard Heck]

commit 2b8ebe9f0d2e408af004e401596bf79d6ce0e76a
Author: Richard Heck <rgh...@lyx.org>
Date:   Wed Jul 22 12:08:20 2015 -0400

    Comment.

diff --git a/src/graphics/PreviewImage.cpp b/src/graphics/PreviewImage.cpp
index 661c8af..12b03f0 100644
--- a/src/graphics/PreviewImage.cpp
+++ b/src/graphics/PreviewImage.cpp
@@ -113,6 +113,9 @@ PreviewImage::Impl::Impl(PreviewImage & p, PreviewLoader & 
l,
 
 PreviewImage::Impl::~Impl()
 {
+       // If these images are generated for a clone, then that may be
+       // because we are previewing. We therefore do not want to delete
+       // them when this Buffer is destroyed.
        if (!ploader_.buffer().isClone())
                iloader_.filename().removeFile();
 }