Bug #361434 --> add a separate access key for the mac system sound. sr=bienvenu

mail/components/preferences/general.xul

@@ -125,11 +125,11 @@
                     orient="vertical" oncommand="gGeneralPane.updatePlaySound();">
           <radio value="0" 
 #ifdef XP_MACOSX
-                 label="&systemsoundMac.label;"
+                 label="&systemsoundMac.label;" accesskey="&systemsoundMac.accesskey;"
 #else
-                 label="&systemsound.label;"
+                 label="&systemsound.label;" accesskey="&systemsound.accesskey;"
 #endif
-                 accesskey="&systemsound.accesskey;" id="system"/>
+                 id="system"/>
           <radio value="1" label="&customsound.label;" 
                  accesskey="&customsound.accesskey;" id="custom"/>
           <hbox class="indent">

mail/locales/en-US/chrome/messenger/preferences/general.dtd

@@ -34,6 +34,7 @@
 <!ENTITY play.accesskey                   "P">
 <!ENTITY systemsound.label                "Default system sound for new mail">
 <!ENTITY systemsoundMac.label             "System Alert Sound">
+<!ENTITY systemsoundMac.accesskey         "y">
 <!ENTITY systemsound.accesskey            "y">
 <!ENTITY customsound.label                "Use the following sound file">
 <!ENTITY customsound.accesskey            "U">