LP1818288 Grid checkboxes emit events

LP1818288 Grid checkboxes emit events

Modify the grid toolbar checkbox onClick handler to emit events instead
of requesting a reference to a function.  This is more consistent with
other event-handling code.

Signed-off-by: Bill Erickson <berickxx@gmail.com>
Signed-off-by: Dan Wells <dbw2@calvin.edu>