showtcheck: will draw a checkbox on the
screen. If Rx contains 1, a check mark will be
printed. If Rx is 0 or undefined, then no check mark will be printed.
showcheck: only draws the widget and does not wait for input.
Parameters:
Rx: The
value of the widget: 1 if checked, 0 if not checked.
name: The name of the tcheck
field defined in tcheck:.