coyote: CGERRORMSG

Description
The purpose of this function is to have a device-independent error messaging function.  
The error message is reported to the user by using DIALOG_MESSAGE if widgets are
supported. Otherwise, the error message is just printed to standard out.
Categories
Utilities
Params
themessage: in, optional, type=string
   This is a string argument containing the error message you want reported. If undefined, 
   this variable is set to the string in the !Error_State.Msg system variable.
Keywords
error: in, optional, type=boolean, default=1
   Set this keyword to cause Dialog_Message to use the ERROR reporting dialog. 
   Note that a longstanding bug in IDL causes the ERROR dialog to be used whether 
   this keyword is set to 0 or 1!
informational: in, optional, type=boolean, default=0
   Set this keyword to cause Dialog_Message to use the INFORMATION dialog instead of the 
   WARNING dialog. Note that a bug in IDL causes the ERROR dialog to be used if this keyword 
   is set to 0!
noname: in, optional, type=boolean, default=0
   Normally, the name of the routine in which the error occurs is prepended to the error
   message. Setting this keyword will suppress this behavior and no routine name will be used.
quiet: in, optional, type=boolean, default=0
   Set this keyword to suppress the DIALOG_MESSAGE pop-up dialog.
title: in, optional, type=string
   Set this keyword to the title of the DIALOG_MESSAGE window. By default the keyword is set to 
   'System Error' unless !ERROR_STATE.NAME equals "IDL_M_USER_ERR", in which case it is set to 
   "Trapped Error'.
 traceback: in, optional, type=boolean, default=1
    Setting this keyword results in an error traceback being printed to standard output with the 
    PRINT command. Use TRACEBACK=0 to turn this functionality off.
Examples
In general, the cgErrorMsg function is not called directly. Rather, it is used in a 
CATCH error handler. Errors are thrown to cgErrorMsg with the MESSAGE command. A typical 
CATCH error handler is shown below::
    Catch, theError
    IF theError NE 0 THEN BEGIN
       Catch, /Cancel
       void = cgErrorMsg()
       RETURN
    ENDIF
Error messages will get into the cgErrorMsg function by throwing an error with the 
MESSAGE command, like this::
    IF test NE 1 THEN Message, 'The test failed.'
Author
FANNING SOFTWARE CONSULTING::
   David W. Fanning
   1645 Sheely Drive
   Fort Collins, CO 80526 USA
   Phone: 970-221-0438
   E-mail: david@idlcoyote.com
   Coyote's Guide to IDL Programming: http://www.idlcoyote.com
History
Change History::
  Written by: David W. Fanning, 27 April 1999.
  Added the calling routine's name in the message and NoName keyword. 31 Jan 2000. DWF.
  Added _Extra keyword. 10 February 2000. DWF.
  Forgot to add _Extra everywhere. Fixed for MAIN errors. 8 AUG 2000. DWF.
  Adding call routine's name to Traceback Report. 8 AUG 2000. DWF.
  Added ERROR, INFORMATIONAL, and TITLE keywords. 19 SEP 2002. DWF.
  Removed the requirement that you use the NONAME keyword with the MESSAGE
    command when generating user-trapped errors. 19 SEP 2002. DWF.
  Added distinctions between trapped errors (errors generated with the
    MESSAGE command) and IDL system errors. Note that if you call ERROR_MESSAGE
    directly, then the state of the !ERROR_STATE.NAME variable is set
    to the *last* error generated. It is better to access ERROR_MESSAGE
    indirectly in a Catch error handler from the MESSAGE command. 19 SEP 2002. DWF.
  Change on 19 SEP 2002 to eliminate NONAME requirement did not apply to object methods.
    Fixed program to also handle messages from object methods. 30 JULY 2003. DWF.
  Removed obsolete STR_SEP and replaced with STRSPLIT. 27 Oct 2004. DWF.
  Made a traceback the default case without setting TRACEBACK keyword. 19 Nov 2004. DWF.
  Added check for window connection specifically for CRON jobs. 6 May 2008. DWF.
  Added QUIET keyword. 18 October 2008. DWF.
  The traceback information was bypassed when in the PostScript device. Not what I
    had in mind. Fixed. 6 July 2009. DWF.
  The QUIET keyword was clearing traceback information. Fixed with help from Phillip Bitzer. 2 Oct 2012. DWF.
  Name changed to cgErrorMsg from Error_Message, 4 November 2013, by David W. Fanning.
Copyright
Copyright (c) 2013, Fanning Software Consulting, Inc.