Log Message:
Update to 2.4.0beta2:

* The toolbar was rewritten with new API.
* 'Prev', 'Print', 'Address', 'Prefs', and 'Account' was added
  to the main toolbar, and 'Prefs' and 'Account' was added to
  the compose toolbar.
* The overflow menu for toolbar was added.
* The width of toolbar buttons was reduced when the labels are
  displayed.
* The option to place toolbar labels at the right of icons was
  added, and it became the default.
* The bug that the window was kept being skipped from window list
  after it became visible with window shading or switching
  workspaces was fixed.
* Some of the UI labels are modified.
* Unix: Symbolic links are now also scanned when scanning MH folders.

* The automatic filtering of new messages in INBOX folder of
  IMAP4 account was implemented.
* The customization of the toolbars was implemented
  ('View - Customize toolbar...', or right-click the toolbar).
* The option to toggle window on trayicon click was added
  (enabled by default on Unix).
* Junk mails are now filtered when incorporating from local spool.
* UTF-8 is forced for headers instead of substituting characters
  if the code conversion failed.
* The crash of the text view when switching between MIME parts
  was fixed.