Syntax:  SET PROMPT DIALOG prompt_dialog

  Sets dialog box prompting.

  By default, LSE uses message window (character-cell) prompting when
  using keys and a dialog box when using the mouse.  You can specify
  the parameter value CCT to always use message window prompting or the
  parameter value window to always use a dialog box.

  This command is ignored when SET PROMPT KEYPAD is VMSLSE.