Try to call

void CListBox::SetHorizontalExtent( int cxExtent );

If the cxExtent is larger than the listbox the scrollbar should
appear.
Do not forget the WS_HSCROLL style!

In Windows API there is an equivalent message:
LB_SETHORIZONTALEXTENT

mfG G=FCnter Nagler
-----------------------------------------------------------------
Dipl.-Ing. Guenter Nagler, Institut fuer HyperMedia Systeme
(IHM),
JOANNEUM RESEARCH Forschungsgesellschaft
Schieszstattgasse 4A, A-8010 Graz, Austria
Tel: ++43 316 832551-32, Fax: ++43 316 824394
email: gnagler@ihm.tu-graz.ac.at

In article <3kk8i2INNl9r@sbusol.rz.uni-sb.de>,
>I need a help!
>I   m writung a program with several listboxes in Visual C++ (MS).
>[...]
>If there is anybody out there to help me, please post me to:
>
>     su11psth@rz.uni-db.de
>
>(I   m sorry for my ugly english |-{ )

Your English is fine, it's your choice of newsgroups and your From:
line that need work.  Tell your sysadmin to fix your news posting
software to list a valid e-mail address instead of:

 From: Mailadresse (Vorname Nachname)

In the meantime please add a "Reply-To:" line to your header, but
don't use the address above.  It bounces (hence I'm posting a followup
instead of just e-mail you the below response).

----canned reply---

Please remember that comp.std.c++ is intended for discussion directly
related to the evolving ANSI/ISO C++ Standard.  Comp.lang.c++ is
available for general discussion of C++ and system-specific newsgroups
are also available for discussion of issues pertaining to MS-DOS, MS
Windows, Mac, UNIX, etc.  Here's something to give you an idea of
where topics like yours might be discussed.  It's from the comp.lang.c++
FAQ available (along with other FAQs) at
ftp://rtfm.mit.edu/pub/usenet/comp.lang.c++/ and
http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html

==============================================================================
SUBSECTION 1B: "Is this the right newsgroup?" (PLEASE READ BEFORE POSTING)
==============================================================================

Comp.lang.c++ is the best place to discuss the C++ language itself (eg,
C++ code design, syntax, style).  Other newsgroups exist for discussion of
topics which are specific to a particular system (eg, MS Windows or UNIX)
or topics which are not directly related to the C++ language (eg, how to
use your compiler).  Here's a list of some very active newsgroups and
excerpts from their Frequently Asked Questions lists.  These excerpts
should give you an idea of the type of topics frequently discussed there.

  comp.os.ms-windows.programmer.tools
     This group is intended for discussions about the selection and use of
     tools for Windows software development.
  comp.os.ms-windows.programmer.misc
     This group is for all other discussions about Windows software
     development.
  [There's one FAQ list for all the comp.os.ms-windows.programmer.* groups]
     FAQ 5.7.1.  Accessing C++ classes in a DLL
     FAQ 6.1.1.  A dialog as an MDI child window [with OWL]
     FAQ 6.2.1.  Disabled menu choices become enabled [with MFC]
     FAQ 8.1.5.  Using STRICT with windows.h
     FAQ 10.  A programmer's bibliography

  comp.os.msdos.programmer
     Much of our traffic is about language products (chiefly from Borland
     and Microsoft).
     FAQ 301. How can I read a character without [waiting for] the Enter key?
     FAQ 412. How can I read, create, change, or delete the volume label?
     FAQ 504. How do I configure a COM port and use it to transmit data?
     FAQ 602. How can a C program send control codes to my printer?
     FAQ 606. How can I find the Microsoft mouse position and button status?
     FAQ 707. How can I write a TSR (terminate-stay-resident) utility?
     FAQ B0. How can I contact [Borland, Microsoft]?
     [note: this FAQ is not available at rtfm.mit.edu; it is at Simtel
            (eg, oak.oakland.edu) in /pub/msdos/info/faqp*.zip and Garbo
            (garbo.uwasa.fi) in /pc/doc-net/faqp*.zip]
  comp.os.msdos.programmer.turbovision [Borland's character-mode framework]

  comp.unix.programmer
     FAQ 4.5)  How do I use popen() to open a process for reading AND writing?
     FAQ 4.6)  How do I sleep() in a C program for less than one second?

  comp.unix.solaris (covers SunOS 4.x and Solaris)
     FAQ 4)  Signal Primer
     FAQ 5)  Waiting for Children to Exit

  gnu.g++.help
     FAQ: Where can I find a demangler?
     FAQ: Getting gcc/g++ binaries for Solaris 2.x
     FAQ: What documentation exists for g++ 2.x?
  gnu.g++.bug [bug reports for g++ -- see the g++ docs]

  comp.lang.c
     FAQ 1.10: I'm confused.  NULL is guaranteed to be 0, but the null
               pointer is not?
     FAQ 2.3:  So what is meant by the "equivalence of pointers and
               arrays" in C?
     FAQ 4.2:  [Why doesn't `printf("%d\n", i++ * i++);' work?]
     FAQ 7.1:  How can I write a function that takes a variable number
               of arguments? [stdarg.h or varargs.h]
     FAQ 10.4: How do I declare an array of pointers to functions returning
               pointers to functions returning pointers to characters?

Also check out the newsgroups comp.graphics, comp.sources.wanted,
comp.programming, and comp.object (its FAQ is an excellent introduction and
overview of OOP terms and concepts).  Remember that comp.std.c++ is for
discussion *directly* related to the evolving ANSI/ISO C++ Standard (see
Q5).

There's rarely a need to crosspost a question to one of the above
newsgroups and comp.lang.c++ (readers in the system-specific newsgroups
aren't programming in machine language, ya know).  It's bad netiquette to
crosspost widely because your problem is "really important".  If you don't
get an answer in the "right" newsgroup and feel you must post here, at
least consider redirecting followups back to the appropriate newsgroup.

Before posting a question to any newsgroup you should read it's FAQ list.
An answer to your question is likely to be there, saving you the time of
posting and saving thousands of other people around the world the time of
reading your question.  People answering an FAQ are likely to be annoyed for
having to answer it for the umpteenth time, or they're likely to be giving
you a wrong or incomplete answer since they haven't read the FAQ either.

Frequently Asked Questions lists are available 24-hours a day via anonymous
ftp (rtfm.mit.edu in /pub/usenet/comp.what.ever) or e-mail server (send a
message with the line "help" to mail-server@rtfm.mit.edu).  See the article
"Introduction to the *.answers newsgroups" in the newsgroup news.answers or
news.announce.newusers (which contains many other must-read articles) for
more information.

Try to call

void CListBox::SetHorizontalExtent( int cxExtent );

If the cxExtent is larger than the listbox the scrollbar should
appear.
Do not forget the WS_HSCROLL style!

In Windows API there is an equivalent message:
LB_SETHORIZONTALEXTENT

mfG G=FCnter Nagler
-----------------------------------------------------------------
Dipl.-Ing. Guenter Nagler, Institut fuer HyperMedia Systeme
(IHM),
JOANNEUM RESEARCH Forschungsgesellschaft
Schieszstattgasse 4A, A-8010 Graz, Austria
Tel: ++43 316 832551-32, Fax: ++43 316 824394
email: gnagler@ihm.tu-graz.ac.at

Hi folks,

I need a help!
I   m writung a program with several listboxes in Visual C++ (MS).
So, i need a short and understandable :-) example to get the horiz.
Scrollbar visible. I   ve just read the informations, available in
several documentations... but I only can make the Scrollbar
visible by setting the HorizontalExtent to a big value, but not in
depent of a new string added to the box. Following the examples, I need
a handle to my listbox-window. But I don   t know how to get this.
If there is anybody out there to help me, please post me to:

     su11psth@rz.uni-db.de

(I   m sorry for my ugly english |-{ )

Thomas