From dc2617130b2e1d7d2b9892fbd7c6e7b60caafb66 Mon Sep 17 00:00:00 2001
From: Bastien Montagne <montagne29@wanadoo.fr>
Date: Wed, 17 Dec 2014 10:20:56 +0100
Subject: [PATCH] Fix: Never write previews for undo steps.

This may eat quite q bit of mem in the end (though nothing critical),
and icons (material ones e.g.) often ended up out of sync after undo.
---
 source/blender/blenloader/intern/writefile.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/source/blender/blenloader/intern/writefile.c b/source/blender/blenloader/intern/writefile.c
index 3dc1fed46c8..bf82a4fa551 100644
--- a/source/blender/blenloader/intern/writefile.c
+++ b/source/blender/blenloader/intern/writefile.c
@@ -2057,7 +2057,8 @@ static void write_lattices(WriteData *wd, ListBase *idbase)
 
 static void write_previews(WriteData *wd, PreviewImage *prv)
 {
-	if (prv) {
+	/* Never write previews in undo steps! */
+	if (prv && !wd->current) {
 		short w = prv->w[1];
 		short h = prv->h[1];
 		unsigned int *rect = prv->rect[1];