The X11R4 and later header files are compatible with C++. The Motif 1.1
header files are usable as is inside extern "C" {...}. However, the
definition of String in Intrinsic.h can conflict with the libg++ or other
String class and needs to be worked around.

Some other projects which can help:

WWL, a set of C++ classes by Jean-Daniel Fekete to wrap X Toolkit widgets, is
available via anonymous FTP from ftp.x.org as R5contrib/WWL-1.2.tar.Z 
or lri.lri.fr (129.175.15.1) as pub/WWL-1.2.tar.Z. It works by building a
set of C++ classes in parallel to the class tree of the widgets.

The C++ InterViews toolkit is obtainable via anonymous FTP from
interviews.stanford.edu. InterViews uses a box/glue model similar to that of
TeX for constructing user interfaces and supports multiple looks on the user
interfaces. Some of its sample applications include a WYSIWIG document editor
(doc), a MacDraw-like drawing program (idraw) and an interface builder
(ibuild). Many of the ideas in InterViews are being folded into Fresco.

THINGS, a class library written at the Rome Air Force Base by the Strategic
Air Command, available as freeware on archive sites.

Motif++ is a public-domain library that defines C++ class wrappers for Motif
1.1 and 1.2; it adds an "application" class for, e.g., initializing X, and
also integrates WCL and the Xbae widget set. This work was developed by
Ronald van Loon <rvloon@motif.xs4all.nl> based on X++, a set of bindings done
by the University of Lowell Graphics Research Laboratory. The current sources
are available from decuac.dec.com (192.5.214.1) in
/pub/X11/motif++.28.jul.93.tar.gz; in the UK check src.doc.ic.ac.uk. Send to
motif++-request@motif.xs4all.nl to be added to the mailing list.

Xm++ is a user interface framework for C++ using the Motif and Athena
toolkits.  Source is on ftp.x.org as contrib/devel_tools/Xm++.0.62.tar.Z; or
email to xmplus@ani.univie.ac.at.

YACL, Yet Another Class Library, by M. A. Sridhar
(sridhar@usceast.cs.scarolina.edu) implements a general-purpose programming
library, using X/Motif and MSWindows for graphical-user-interface needs.
Sources are on ftp.cs.scarolina.edu (129.252.131.11), in /pub/yacl.  Version
1.5 was released 3/96.

Qt is a complete and well-developed object-oriented framework for developing
graphical user interface applications using C++. Version 1.0 was released
8/96. For information, contact Troll Tech at sales@troll.no, fax +47
22646949, or http://www.troll.no/qt/ . A mailing list exists; send the single
word "subscribe" to qt-interest-request@nvg.unit.no.

Modello is an object-oriented interface to the Display PostScript System that
is designed to provide a foundation for WYSIWYG applications and the tools to
built support them.  Files are in ftp://ftp.x.org/contrib/devel_tools/DPS/ .
A beta release became available 4/96.

V is a portable C++ GUI Framework intended to develop a wide variety of
applications on different graphical interface platforms. Most standard GUI
objects are supported by V, including windows with menus, status bars, tool
bars, and a drawing canvas; modal and modeless dialogs with the most common
controls (buttons, lists, labels, text entry, check and radio buttons, etc.);
and portable printing support.  Sources are on http://www.cs.unm.edu/~wampler
and on ftp://sunsite.unc.edu/pub/Linux/X11/libs/v-1.05.tar.gz . Version 1.05
was released 2/96.

Xl is a protocol implementor for C++; see ftp://humm.whoi.edu/pub/Xl/ .

The xarm C++ wrapper to Motif is at 1.2.1 [12/95]; it is at
ftp://sunsite.unc.edu/pub/Linux/X11/devel/Xarm-1.2.1.tar.gz .

The Theseus++ User Interface Toolkit Release 2.5.2 is a copylefted C++
user-interface toolkit for X and Motif. Sources are on archimedes.igd.fhg.de
in /pub/Theseus++/theseus++-2.5.2.

The source code examples for Doug Young's "Object-Oriented Programming with
C++ and OSF/Motif" [ISBN 0-13-630252-1] do not include "widget wrappers" but
do include a set of classes that encapsulates higher-level facilities
commonly needed by Motif- or other Xt-based applications; check ftp.x.org in
R5contrib/young.cxx.tar.Z. This software is now being produced commercially
as "ViewKit" by SGI; ICS is a reseller (http://www.ics.com/ ).

The Hungry Programmers have written a ViewKit toolkit; the Hungry ViewKit is
available under Gnu Public License terms from:
ftp://pain.csrv.uidaho.edu/pub/hungry/viewkit/ . Info: hungry@uidaho.edu.

UIT is a set of C++ classes embedding the XView toolkit; it is intended for
use with Sun's OpenWindows Developers Guide 3.0 builder tool. Sources are on
ftp.x.org as R5contrib/UIT.tar.Z. This tool may since have become GIT (GNU
Interactive Tools).

The Andrew User Interface System provides a rich C++ toolkit.  Version 6.3 is
on the R6 tapes.  You may be able to use the Remote Andrew Demo service to
try this software; try "finger help@atk.itc.cmu.edu" for help. Version 7.4 is
now [8/96] available; see ftp://ftp.andrew.cmu.edu/pub/AUIS/ .

The DD++ library is a C++ wrapper for the Motif 1.2 drag and drop preregister
protocol; sources are on ftp.x.org:contrib/libraries/DD++1.2.tar.Z [3/95].

A "minimal Motif C++ library wrapper" (using GNU Public License terms) is
available from ftp.lasermoon.co.uk in ftp.lasermoon.co.uk as /pub/products/Xad.
Information is available from xmmin@sytek.it.

Rogue Wave offers "View.h++" for C++ programmers using Motif. Info:
1-800-487-3217 or +1 503 754 2311.

wxWindows from the Artificial Intelligence group at Edinburgh University is
available for Motif and Windows NT/95. It includes a GUI builder.

A product called "Commonview" by Glockenspiel Ltd, Ireland, apparently is a
C++-based toolkit for multiple window systems, including PM, Windows, and
X/Motif. This product is one of an increasing number of C++ toolkits which
offer X (typically Motif) as one user-interface choice.

Xv++ is sold by Qualix (415-572-0200; fax -1300); it implements an interface
from the GIL files that Sun's OpenWindows Developers Guide 3.0 produces to
Xview wrapper classes in C++.

The Microsoft Foundation Class (MFC) library from Bristol (info@bristol.com)
is a GUI class library for Windows, Mac, and Motif applications.

Pure Software's (formerly ParcPlace's; formerly Solbourne's) Object Interface
is a full user-interface toolkit (from Xlib up) developed for C++; it offers
both OpenLook and Motif visuals. The OI package includes a builder.