165151 r=cavin sr=bienvenu Throw an alert in case parsing folder cannot get folder lock

mailnews/base/resources/locale/en-US/messenger.properties

@@ -70,6 +70,7 @@ confirmFolderDeletionForFilter=Deleting the folder '%S' will disable its associa
 alertFilterChanged=Filters associated with this folder will be updated.
 filterDisabled=The folder '%S' could not be found, so filter(s) associated with this folder will be disabled. Verify that the folder exists, and that filters point to a valid destination folder.
 filterFolderDeniedLocked=The messages could not be filtered to folder '%S' because another operation is in progress.
+parsingFolderFailed=Unable to open the folder %S because it is in use by some other operation.Please wait for that operation to finish and then select the folder again. 
 alertFilterCheckbox=Do not warn me again.
 compactFolderDeniedLock=The folder '%S' cannot be compacted because another operation is in progress. Please try again later.
 compactFolderWriteFailed=The folder '%S' could not be compacted because writing to folder failed. Verify that you have enough disk space, and that you have write privileges to the file system, then try again.
@@ -77,7 +78,6 @@ filterFolderWriteFailed=The messages could not be filtered to folder '%S' becaus
 copyMsgWriteFailed=The messages could not be moved or copied to folder '%S' because writing to folder failed. To gain disk space, from the File menu, first choose Empty Trash, and then choose Compact Folders, and then try again.
 cantMoveMsgWOBodyOffline=While working offline, you cannot move or copy messages that were not downloaded for offline use. From the Mail window, open the File menu, choose Offline, then choose Work Online, and then try again.
 
-
 folderRenameFailed=The folder could not be renamed. Perhaps the folder is being reparsed, or the new name is not a valid folder name.
 # LOCALIZATION NOTES(verboseFolderFormat): %1$S is folder name, %2$S is server name
 verboseFolderFormat=%1$S on %2$S