NAME:
    qinput
 PURPOSE: (one line)
    Prompt user for input using a popup widget.
 DESCRIPTION:
    This popup widget is meant to be used anywhere you might need input
       from a user.  Functionally, it replaces "read,prompt='Input:',ans"
       that would be used in a older style input methodology.  It can
       be used in widget and non-widget programs alike but is probably
       better used within widget programs.
 CATEGORY:
    Widgets
 CALLING SEQUENCE:
    result = qinput( [keywords] )
 INPUTS:
 OPTIONAL INPUT PARAMETERS:
 KEYWORD INPUT PARAMETERS:
    DEFAULT  = Default value for input.  If not supplied the default has no
                  value which is interpreted differently for each input type.
    GROUP_LEADER = Group leader id. If present, qinput runs as a modal
                  application. Otherwise, it runs as a non-modal application.
    PROMPT   = Character string to be displayed as a prompt.
    TITLE    = Title for the widget.

    FLOATING = Set this keyword to accept a floating-point value.
    INTEGER  = Set this keyword to accept an integer value.
    LONG     = Set this keyword to accept a longword integer value.
    STRING   = Set this keyword to accept a string value.
 OUTPUTS:
    result = the returned value.
 KEYWORD OUTPUT PARAMETERS:
    CANCELLED - Flag, if set means the input from user was cancelled and
                   you should not process the returned value.
 COMMON BLOCKS:
 SIDE EFFECTS:
    Suspends other widget event generation.  A user response is required.
 RESTRICTIONS:
  Note: the default value you supply needs to be consistent with the
     variable type you select if you want defaulting to work properly.
     For example, don't give it a string if you want float values or you
     may not get back what you intend.
 PROCEDURE:
 MODIFICATION HISTORY:
    Written by Doug Loucks, Lowell Observatory, July 27, 1994.
    2002/03/06, Marc W. Buie, fixed bug in handling keyword type switches,
                  added DEFAULT keyword.
    2004/04/12, Doug Loucks, Cleaned up event handling. Added code that uses
                  pointer variables. Added a 'Cancel' button.
    2006/11/25, Nathaniel J. Cunningham, added CANCELLED keyword so that
                  cancelling can be differentiated from null string.
    2008/10/30, MWB, slight rewrite of internals for robust state structure.
                  Also, now exclusively returns a scalar regardless of type.