Comment 89 for bug 119899

Test result with Tb trunk 2008/8/09 build on MS Win-XP SP3, with Gmail IMAP.

(0) Filter for IMAP account : If User-Agent contains 'Thunderbird' add tag
    No automatic download option is enabled
(1) Initial (Inbox of the IMAP account)
    - Tools/Account Settings/Server Settings/Advanced/Offline
      "Select this folder for offline" : Unchecked
    (1-a) Upon download => Tag was added
          (All headers are downloaded because without header choice upon FETCH)
    (1-b) Manual "Run filters on" => Tag was NEVER added => Remove all tags
          (View source of mail displays the User-Agent: header)
(2) Enable Offline-use, and execute "Download Now"
    - Tools/Account Settings/Server Settings/Advanced/Offline
      "Select this folder for offline" : Checked
      Execute "Download Now"
    - Manual "Run filters on" => Tag was added => Remove all tags
(3) Disable Offline-Use
    - Tools/Account Settings/Server Settings/Advanced/Offline
      "Select this folder for offline" : Unchecked
(4) Restart Tb
(5) Manual "Run filters on" on Inbox => Tag was added

Why Tag was added at step (5) even though offline-use is off?
Tb tried to read downloaded mail data for offline-use when "Run Filters On" at step (1)?