tk_messageBox - pops up a message window and waits for user response.

       This procedure creates and displays a message window with an application-specified message, an icon and a
       set  of  buttons.  Each of the buttons in the message window is identified by a unique symbolic name (see
       the -type options).  After the message window is popped up, tk_messageBox waits for the  user  to  select
       one of the buttons. Then it returns the symbolic name of the selected button.

       The following option-value pairs are supported:

       -commandstring
              Specifies  the  prefix  of  a  Tcl  command  to invoke when the user closes the dialog. The actual
              command consists of string followed by a space and the name of the button clicked by the  user  to
              close the dialog. This is only available on macOS.

       -defaultnameName  gives  the symbolic name of the default button for this message window ( “ok”, “cancel”, and
              so on). See -type for a list of the symbolic names.  If this option is not  specified,  the  first
              button in the dialog will be made the default.

       -detailstring
              Specifies  an  auxiliary  message  to  the  main message given by the -message option. The message
              detail will be presented beneath the main message and, where  supported  by  the  OS,  in  a  less
              emphasized font than the main message.

       -iconiconImage
              Specifies  an  icon  to  display. IconImage must be one of the following: error, info, question or
              warning. If this option is not specified, then the info icon will be displayed.

       -messagestring
              Specifies the message to display in this message box. The default value is an empty string.

       -parentwindow
              Makes window the logical parent of the message box. The message box is displayed  on  top  of  its
              parent window.

       -titletitleString
              Specifies  a  string  to  display  as  the title of the message box. The default value is an empty
              string.

       -typepredefinedType
              Arranges for a predefined set of buttons to be displayed. The following values  are  possible  for
              predefinedType:

              abortretryignore  Displays three buttons whose symbolic names are abort, retry and ignore.

              ok                Displays one button whose symbolic name is ok. This is the default.

              okcancel          Displays two buttons whose symbolic names are ok and cancel.

              retrycancel       Displays two buttons whose symbolic names are retry and cancel.

              yesno             Displays two buttons whose symbolic names are yes and no.

              yesnocancel       Displays three buttons whose symbolic names are yes, no and cancel.

              set answer [tk_messageBox -message "Really quit?" \
                      -icon question -type yesno \
                      -detail "Select \"Yes\" to make the application exit"]
              switch -- $answer {
                  yes exit
                  no {tk_messageBox -message "I know you like this application!" \
                          -type ok}
              }

       message box

Tk                                                     4.2                                    tk_messageBox(3tk)

       tk_messageBox - pops up a message window and waits for user response.

tk_messageBox ?optionvalue...?
________________________________________________________________________________________________________________