add_radio name onval offval variable value command
Multiple radio buttons are grouped together to form a set of which any one
button can be activated at any one time. The
add_radio command adds
commands to menus in a similar fashion to the
add_command command, but
has two additional arguments; variable and value.
Each radio button within a group uses the same variable with differing
values. When a radio button is selected the global Tcl variable is set
with the associated value and the command is executed. A useful tip is
that the contents of the variable may be passed to the command as an
As each group can specify its own variable, multiple radio button groups are possible .