--- mtpaint-3.19/src/png.c~	2007-11-11 16:48:32.000000000 +0100
+++ mtpaint-3.19/src/png.c	2007-12-16 23:33:19.000000000 +0100
@@ -3990,7 +3990,7 @@
 
 #else /* Linux */
 
-#define HANDBOOK_BROWSER "firefox"
+#define HANDBOOK_BROWSER "xdg-open"
 #define HANDBOOK_LOCATION "/usr/doc/mtpaint/index.html"
 #define HANDBOOK_LOCATION2 "/usr/share/doc/mtpaint/index.html"