Bug 397928: let mailnews.thread_pane_column_unthreads default to false, but for SM only; r=bienvenu, sr=neil

mail/app/profile/all-thunderbird.js

@@ -197,6 +197,9 @@ pref("mailnews.headers.minNumHeaders", 0); // 0 means we ignore this pref
 // 0-Accept, 1-dontAcceptForeign, 2-dontUse
 pref("network.cookie.cookieBehavior", 0);
 
+// if true, any click on a column header other than the thread column will unthread the view
+pref("mailnews.thread_pane_column_unthreads", true);
+
 /////////////////////////////////////////////////////////////////
 // End seamonkey suite mailnews.js pref overrides
 ///////////////////////////////////////////////////////////////// 

mailnews/mailnews.js

@@ -387,7 +387,7 @@ pref("mail.toolbars.showbutton.junk", true);
 pref("mail.toolbars.showbutton.print",false);
 pref("mail.toolbars.showbutton.stop", false);
 
-pref("mailnews.thread_pane_column_unthreads", true);
+pref("mailnews.thread_pane_column_unthreads", false);
 
 pref("mailnews.account_central_page.url", "chrome://messenger/locale/messenger.properties");