COPY BLOCK TO BUFFER                                               <Alt>+C

  You can use this option to copy a section of the screen to a buffer for
  later retrieval. Use the arrow keys, <Home>, <End>, <PgUp> and <PgDn> to
  resize the box specifying the area to be copied. <Tab> toggles between the
  top left and the bottom right corners when resizing. Press <Enter> when
  you are ready to copy, or press <Esc> to abort the operation.

  Once you press <Enter>, you will be required to choose which of the nine
  buffers to copy to. The ones marked with an X are unused, the ones marked
  with a . contain data. You can still copy into buffer containing data,
  however the data that was previously there will obviously be lost.

  Note that this copy works in "pixels", so any normal characters in the
  area to be copied will be lost.