a theme for clockmail contains the following:

* The theme is contained within a directory.
* The layout and filenames for images are specified in a file
  named clockmaildata (see the example included in the source).
* Only the Background image is required, all other items are
  optional. eg: you can omit seconds, or even the mail part if
  you only want a clock, etc.
* A clockmaildata file contains 1 or 2 sections. [Horizontal] is
  required, [Vertical] is used if the theme supports orientation.
  Both sections support all the flags below.
* The background image should always contain an alpha channel,
  even if it is not a shaped theme.

Internationalization:
  Item_* types support internationalization by adding another tag
  to the clockmaildata file and supplying a suitable image.
  Example:
    To internationalize A day of week item for 'es' do this:

    Keep the default line:     Item_Week_Text=week.png 2 20
    and add a translated line: Item_Week_text[es]=weekes.png
        (do not add coordinates to the translated lines)

  Note: The translated image should be the same size as the default,
        and in the case of Item_Mail must contain the same number
        of animation frames.

Mail_Image=filename sections x y
  filename: Name of the image file for mail, this file contains
            images vertically the last image is the one displayed
            to show mail, all the others are animated (flipped
            through) to show new mail.
  sections: Total number of mail pics within the image file.
  x, y: Coordinates to place the image within the window.

Digit_Small/Large=filename
  filename: Image file, contains horizontally the digits 0 through
            9 and a blank space.

Number_Hour/Minutes/Seconds/Year/Month/Day=Large/Small x y
  Large/Small: The digit to use for this number, Large or Small must
               have been specified with the Digit_* line (above).
  x, y: Coordinates to place the numbers within the window.

Number_Mail=Large/Small x y
  Same as above, except this is a number for the amount of mail in
  the mailbox (in Kbytes). It requires space for 4 digits long.

Item_Week_Text=filename x y
  filename: Image file, contains vertically the days of the week
            from Sunday through Saturday (7).

Item_Month_Text=filename x y
  filename: Image file, contains vertically the months of the year (12).
            (January - December)

Item_Mail_Percent=filename sections x y
  filename: Name of the image file for percent of mail, this file contains
            images vertically that represent the percent that the mailbox is
            full. The images should represent 0 to 100%, there can be any
            number of images.
            (for instance 6 images for 20% increments: 0,20,40,60,80,100)
  sections: Total number of images within the image file.
  x, y: Coordinates to place the image within the window.