cell-select in sequence-dialog-items

[owens@jonquil.uchicago.edu (Christopher Owens)]

I'm noticing that, contrary to my intuitive expectations,
sequence-dialog-items in MCL 2.0 do not call CELL-SELECT when the user
selects a cell by clicking on it.  Cells become highlighted and added
to the list returned by SELECTED-CELLS, but the CELL-SELECT method
itself does not appear to be called.

I had hoped to specialize an :after method for this generic function
(and for cell-deselect) on a subclass of sequence-dialog-item that
would accomplish the behavior of activating a few buttons when and
only when one or more items in a table were selected.  It seems like
CELL-SELECT and CELL-DESELECT are a more logical place to put this
behavior than on VIEW-CLICK-EVENT-HANDLER, since sometimes cells might
be selected or deselected other than by clicking. (i.e. by typing
characters as in the select file dialog, or by program action)