http://www.perlmonks.org?node_id=11111133


in reply to Re^3: Tk programmatically monitor change in Listbox
in thread Tk (Tcl::Tk) programmatically monitor change in Listbox

See Re^5: Tk programmatically monitor change in Listbox for hints, but i wouldnt say it was documented as you might like it, but the basis for those tests is found in the TCL pod.