declare
fun {NewProgWindow CheckMsg}
   InfoHdl See={NewCell true}
   H D=td(title:"Progress monitor"
          label(text:nil handle:InfoHdl)
          checkbutton(
             text:CheckMsg handle:H init:true
             action:proc {$} See:={H get($)} end))
in
   {{QTk.build D} show}
   proc {$ Msg}
      if @See then {Delay 50} {InfoHdl set(text:Msg)} end
   end
end