The default bindings handle the <Button-1> event by first starting the
editing session for the clicked cell and then clearing the cell
selection and setting it to the cell just clicked. You can override
this standard behavior by inserting the following code into your
-editstartcommand procedure:
set cellIdxList [$tbl curcellselection]
after 0 [list $tbl cellselection set $cellIdxList]