diff --git a/mozilla/modules/libpref/src/init/all.js b/mozilla/modules/libpref/src/init/all.js
index 9523085ff79..a58ae96a8b5 100644
--- a/mozilla/modules/libpref/src/init/all.js
+++ b/mozilla/modules/libpref/src/init/all.js
@@ -717,6 +717,9 @@ pref("update_notifications.enabled", true);
 pref("update_notifications.provider.0.frequency", 7); // number of days
 pref("update_notifications.provider.0.datasource", "chrome://communicator-region/locale/region.properties");
 
+// 0 opens the download manager
+// 1 opens a progress dialog
+// 2 and other values, no download manager, no progress dialog. 
 pref("browser.downloadmanager.behavior", 0);
 
 // if true, allow plug-ins to override internal imglib decoder mime types in full-page mode