Merge changes from emacs-23 branch

[bpt/emacs.git] / nt / INSTALL

diff --git a/nt/INSTALL b/nt/INSTALL
index a000b21..da7ad56 100644 (file)
--- a/nt/INSTALL
+++ b/nt/INSTALL
@@ -290,6 +290,23 @@
   If GTK 2.0 is installed, addpm will arrange for its image libraries
   to be on the DLL search path for Emacs.
 
   If GTK 2.0 is installed, addpm will arrange for its image libraries
   to be on the DLL search path for Emacs.
 

+  For PNG images, we recommend to use versions 1.4.x and later of
+  libpng, because previous versions had security issues.  You can find
+  precompiled libraries and headers on the GTK download page for
+  Windows (http://www.gtk.org/download-windows.html).
+
+  Versions 1.4.0 and later of libpng are binary incompatible with
+  earlier versions, so Emacs will only look for libpng libraries which
+  are compatible with the version it was compiled against.  That
+  version is given by the value of the Lisp variable `libpng-version';
+  e.g., 10403 means version 1.4.3.  The variable `image-library-alist'
+  is automatically set to name only those DLL names that are known to
+  be compatible with the version given by `libpng-version'.  If PNG
+  support does not work for you even though you have the support DLL
+  installed, check the name of the installed DLL against
+  `image-library-alist' and the value of `libpng-version', and
+  download compatible DLLs if needed.
+

 * Experimental SVG support
 
   SVG support is currently experimental, and not built by default.
 * Experimental SVG support
 
   SVG support is currently experimental, and not built by default.