[gimp] file-png: Update comment for png_set_IHDR()

[Mukund Sivaraman <muks src gnome org>]

commit ae654a7aaea25a1ae445b702f57792562e1d3763
Author: Mukund Sivaraman <muks banu com>
Date:   Thu May 5 20:47:53 2011 +0530

    file-png: Update comment for png_set_IHDR()

 plug-ins/common/file-png.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/plug-ins/common/file-png.c b/plug-ins/common/file-png.c
index f798999..dd28dc2 100644
--- a/plug-ins/common/file-png.c
+++ b/plug-ins/common/file-png.c
@@ -1336,8 +1336,8 @@ save_image (const gchar  *filename,
       return FALSE;
     }
 
-  /* Set the image dimensions, bit depth, interlacing and compression */
-
+  /* Note: png_set_IHDR() must be called before any other png_set_*()
+     functions. */
   png_set_IHDR (pp, info, drawable->width, drawable->height,
                 bit_depth,
                 color_type,