write-headers-to-file

Called when the buffer is being saved to a file. The return value is #t if there are no errors. Override this method to add custom header data to a file, but always call the inherited method so that it can write its own extra headers.

To write a header item, call begin-write-header-footer-to-file, passing a box for an integer. Then write the header data and end by calling end-write-header-footer-to-file, passing back the integer that was put into the box. Follow this procedure correctly or the file will be corrupted.

• (send a-wx:media-buffer write-headers-to-file stream) -> boolean
      stream : wx:media-stream-out% object

  Does nothing.