MANAGE_WIDGET
  Makes the specified widget visible, provided the specified widget's parent
  is visible.
  Syntax
     MANAGE_WIDGET (widget [, widget...])
  Parameters
     widget               The widget instance you want to manage.
  Comments
     MANAGE_WIDGET causes the specified widget's parent to become
     responsible for determining the widget's space requirements.  It also
     causes the parent to determine the widget's visibility depending upon
     the MAPPED_WHEN_MANAGED setting for the widget.
  Example
     The following statement manages the widget instance assigned to the
     variable "sample_x_keypad":
     MANAGE_WIDGET (sample_x_keypad);
  Related Topics
     CREATE_WIDGET   GET_INFO(WIDGET_VARIABLE)  LOWER_WIDGET
     RAISE_WIDGET    REALIZE_WIDGET   SET(MAPPED_WHEN_MANAGED)
     UNMANAGE_WIDGET