From: Wolfgang Rosenauer
Subject: NonGnome/KDE integration
References:
https://bugzilla.novell.com/show_bug.cgi?id=170055
Caveats: desktop file name of Firefox is hardcoded to MozillaFirefox

diff --git a/mozilla/browser/base/content/nsContextMenu.js b/mozilla/browser/base/content/nsContextMenu.js
index 53bc215..725990b 100644
--- a/mozilla/browser/base/content/nsContextMenu.js
+++ b/mozilla/browser/base/content/nsContextMenu.js
@@ -317,7 +317,9 @@ nsContextMenu.prototype = {
     if (AppConstants.HAVE_SHELL_SERVICE) {
       // Only enable Set as Desktop Background if we can get the shell service.
       var shell = getShellService();
-      if (shell)
+      var env = Components.classes["@mozilla.org/process/environment;1"]
+                          .getService(Components.interfaces.nsIEnvironment);
+      if (shell && env.get('DESKTOP_SESSION') == "gnome")
         haveSetDesktopBackground = shell.canSetDesktopBackground;
     }