This command is a Tcl procedure provided as part of the Tk script library.
It takes as arguments the path names of one or more listbox widgets,
or the value Listbox.
For each named widget, tk-listbox-single-select modifies the
bindings of the widget so that only a single element may be selected
at a time (the normal configuration allows multiple elements to be
If the keyword Listbox is among the window arguments,
then the class bindings for listboxes are changed so that all
listboxes have the one-selection-at-a-time behavior.