--- a/mail/base/content/mail3PaneWindowCommands.js
+++ b/mail/base/content/mail3PaneWindowCommands.js
@@ -352,20 +352,22 @@ var DefaultController =
           goSetAccessKey(command, whichText + "AccessKey");
         }
         if (numSelected > 0)
         {
           if (!gFolderDisplay.getCommandStatus(nsMsgViewCommandType.cmdRequiringMsgBody))
             return false;
 
           // Check if we have a collapsed thread selected and are summarizing it.
-          // Also check that we're not displaying a message, which handles the
-          // case where we failed to summarize the selection and fell back to
-          // displaying a message.
-          if (!gMessageDisplay.singleMessageDisplay && command != "cmd_applyFiltersToSelection")
+          // If so, selectedIndices.length won't match numSelected. Also check
+          // that we're not displaying a message, which handles the case
+          // where we failed to summarize the selection and fell back to                  // displaying a message.
+          if (gFolderDisplay.selectedIndices.length != numSelected &&
+              command != "cmd_applyFiltersToSelection" &&
+              gDBView && gDBView.currentlyDisplayedMessage == nsMsgViewIndex_None)
             return false;
           if (command == "cmd_reply" || command == "button_reply" ||
               command == "cmd_replyall" ||command == "button_replyall")
             return IsReplyEnabled();
           if (command == "cmd_replylist" || command == "button_replylist")
             return IsReplyListEnabled();
           return true;
         }