This article contains the answers to some Frequently Asked Questions (FAQ)
often seen in the LessTif mailing list and posted to the newsgroup
comp.windows.x.motif.
It is posted to help reduce volume in the LessTif mailing list and to
provide hard-to-find information of general interest.
This article includes answers to the following questions, which are loosely
grouped into categories. Questions marked with a + indicate questions new to
this issue; those with significant changes of content since the last issue are
marked by !
This FAQ was last updated on $Date: 2001/11/24 14:06:37 $
What is LessTif?
LessTif is a clone of the
Motif® toolkit.
Currently LessTif is partially implemented with most of the API in place.
Saying this a lot of the internal functionality is still missing.
Compatibility can have several degrees,
the ultimate one being binary compatibility.
This is the one we're aiming for.
This can be tested even today on most platforms on which shared libraries
are supported :
if you also have Motif® shared libraries,
you can choose which library to use by setting an environment variable
such as LD_LIBRARY_PATH prior to executing an application.
The primary objectives have been to develop the widget code of the
LessTif Toolkit.
Intermittently, the window manager (mwm)
and the combination of UIL compiler and libMrm are being worked on.
Volunteers to advance one or more parts of LessTif development,
or for writing documentation without an OSF, X/Open or The Open Group
copyright on it, are always welcome.
The same web pages can point you to quite a few
CD-ROM manufacturers
which put a version of LessTif on some of their products.
Many free Unix (RedHat, Debian, SuSE, Walnut Creek FreeBSD, ...)
are among them.
Who is developing LessTif?
A few Internet based individuals as listed in
core.html.
Nobody is paid to work on it, all is effort by volunteers.
Look for an all-time list of authors in the AUTHORS file in
the LessTif distribution, while CREDITS acknowledges the contributions
of various other people.
Keeping a list of developers for each widget is not really possible
mainly because the we're not fanatic about ownership of a widget.
We do keep in touch enough to know who's messing with what
so we don't overlap too much.
You should be able to compile and run your code,
how well it works is another matter...
If it doesn't, then we're very interested in hearing about
what doesn't work and why (we can't fix bugs that we don't know about),
and we're even more interested in a fix.
If your favorite application does work,
please tell us so we add it to the list of apps known to work.
Will LessTif be Motif1.2 Compliant?
Yes, this is the first major step.
Up to now we are very close, all interfaces are in place,
we might only have to fight against some remaining bugs ...
In early 1997 however, someone asked whether submissions for 2.0 or
CDE widgets would be accepted.
Of course !
Therefore, we expanded the source directory tree to make it easy to
add new stuff, and to build several versions of the library (and the
corresponding tools). So if anybody has a widget, or an application,
to offer which can advance us in the 2.x or CDE areas, please E-mail us.
Somewhere along 1997 we actually started building 2.0 compliant widgets.
More of them are needed though.
Will LessTif be Motif2.0 Compliant?
Probably not fully. Since 2.0 is now gone and has been replaced by
the OpenGroup's Motif version 2.1 we will also no longer focus
on a 2.0 compatible release. Especially WRT CSText and the C++ extensions -
unless someone will donate implementations of these we will probably never
get them!
Will LessTif be Motif2.1 Compliant?
Yes, even though we're convinced that this might still take some time.
Some of the new features in 2.x are not exactly easy stuff !
Having some of the widgets implemented can make us get away with
a lot of stuff : some applications just need one of the new widgets.
If applications use some of the flashy new features such as renderings,
...
What about CDE?
We earlier made room for CDE compatible widgets and applications,
and talked to the people of the eXode project
(their homepage is at
http://www.simplicity.net/exode
)
They basically didn't want to use too much of the 2.* stuff
(some of it is rather buggy in OSF releases); also they really wanted the
core of eXode to run on top of LessTif.
Meanwhile we also have to make a similar statement as in the answer for
question
Will LessTif be Motif2.0 Compliant?:
Our main focus is meanwhile Motif 2.1 compliance!
Is UIL (User Interface Language) supported?
Not really.
Though there is some old code in place already
it's unlikely you succeed with a project using it.
Actually there are two versions of the uil compiler around:
one is built as uil while the other executable is named
newuil. The latter uses libUil as opposed to
the older one which uses it's own code base.
What is LessDox?
LessDox is the shortened version of the LessTif Documentation Project.
Any previous reference to "LDP" is now dropped because of the
conflict with the "Linux Documentation Project".
What Platforms is LessTif on?
A more accurate list is available in an
extraneous file.
Here's an excerpt, with version numbers stripped for brevity:
Linux, FreeBSD, NetBSD, OpenBSD, BSDi (BSD/OS), Sun (SunOS, Solaris),
MkLinux, OS/2, AIX, Digital UNIX/Compaq Tru64, HP/UX,
Windows NT, Windows 95 (with cygwin32)
Is there a pre-built library available for My Platform?
Might be, we started doing that as of early March, 1997.
The core team (and some other brave guys) are providing
compiled images.
Currently we don't have a document describing how to install them,
but they're there for Linux, FreeBSD, OS/2.
The INSTALL file found in the source
distribution and on the web explains how to install it.
Note we'll only refresh these binary distributions at
release time (at least for major releases).
Make sure that you do get a binary version,
if that's what you're interested in; not the source distribution.
We also have a list of
CD-ROMs which include LessTif distributions.
For several platforms there are also third-party binary packages
available. Further information can be found in
INSTALL and
on our
download pages.
Do I need to have imake/xmkmf?
No. LessTif used to work with those,
but they became more of a problem than a solution,
so we switched to GNU autoconf, which has the additional capability
to find out many many things about the target platform while
auto-configuring itself.
Around December 1997 we also started to work with libtool and automake,
two more free tools.
They should solve the portability problems with building shared libraries
on multiple platforms for us.
You'll find this in distributions of LessTif starting with release 0.85.
We use libtool for keeping the complexities of building and installing
shared libraries out of LessTif. Therefore, if LessTif doesn't build a working
shared library on some platform, you may want to check whether libtool already
supports this platform.
Contact the libtool mailing list if you're interested in details about
the platforms supported by libtool. http://www.opengroup.org/onlinepubs/7908799/xsh/limits.h.htmlA link to libtool homepage is on our
links page.
Can I build a Static Library?
Even for this we use libtool;
but yes, you can on all platforms we can think of.
By default building these is disabled. Check out the
INSTALL document how to
actually build them (hint: you have use a configure switch).
For more information on this topic check out the
INSTALL document.
Why does it say I need X11r5 or higher when I have r6 ?
Several people have reported build problems;
the configure script looks for an X distribution and then checks whether
it is X11R5 or X11R6.
On some systems the configure script stops, saying
configure: error: You must have X11 Revision 5 or higher to compile LessTif
while the system actually has X11R6.
Apparently this has to do with installations of Linux, in which
the include files (under /usr/include) often contain symbolic links
to the source directories (either on disk or on CD-ROM).
In such a situation, if one either removes the CD-ROM, or cleans up
/usr/src, the effect will be dangling symbolic links under /usr/include
which confuse our configure script.
The solution is obvious : make sure that your include files don't contain
symbolic links to nonexistent files.
Another possibility is that you simply forgot to install the X11 development
package (e.g. X11-devel RPM) so that the related headers are not yet installed
on your system.
On the other hand, please make sure that you've built the entire
distribution with the same configuration.
Not clear ?
After running the "configure" command with its options,
you should ideally run "make clean".
Otherwise e.g. clients/Motif-1.2/mwm/Makefile may be configured
such that it looks for stuff that isn't there in lib/Xm/* .
Why does configure fail?
There are some circumstances when configure fails to run, or produces
wrong results:
You have an old (broken/incomplete) config.cache (config.status) file left over.
Delete those! Or if you have a recent set of the auto* tools
installed (See
INSTALL.html)
run the CVSMake script, and then configure again.
configure (and the generated Makefiles) won't work if the build directory
resides in a path which has embedded blanks, e.g. "/usr/work/Fine Software".
The simple and only solution is to move it to another path.
If you get some strange results also check whether you have some
strange settings in the environment which may cause those.
Some related variables are CC, CFLAGS, LIBS, ...
Application fails to start
Your application fails to start and you get a quite "sophisticated"
error message like the following:
Error: PANIC: no realize procedure specified for this widget.
or
Error: attempt to add non-widget child "DropSiteManager" to parent
"xmfoo" which supports only widgets
We've seen this happen when the order of libraries upon linking was incorrect.
The correct order is :
-lXm -lXt -lX11
(see also
Question 5.1)
If you built this application please link it again, otherwise
notify the maintainer.
Check out _LtCheckClassOfVendorShell()
and _LtXmFixupVendorShell() in lib/Xm/Vendor.c.
A suitable test is in /test/Xm/Vendor/test4.c.
Also related messages should be in the
mailinglist archive.
The following explanation was a submission from
Martin Simmons:
The linking order problems are caused by these two symbols:
vendorShellClassRec
vendorShellWidgetClass
which are defined *AND* referenced in both -lXm and -lXt. Somehow you have to
convince the linker to use the -lXm definitions to satisfy the references in
both -lXm and -lXt. The -lXt definitions should not be used.
For typical elf-based dynamic loaders (Linux, Solaris etc), this is done by
passing '-lXm -lXt' to the linker, which adds them both as SO_NEEDED sections
to the executable. At runtime, the dynamic loader collects symbols from each
SO_NEEDED section in the order it finds them, discarding symbols it already
knows, and then fixes the references in all the loaded libraries using that
combined symbol table.
For typical static linkers, it is also done by specifying '-lXm -lXt' to the
linker. In this case, the linker extracts some .o's from -lXm which contain
user-referenced symbols and eventually ends up extracting -lXm:Vendor.o due to
internal references in -lXm. It then does the same for -lXt, but doesn't need
to extract -lXt:Vendor.o because it doesn't define anything that is still
undefined.
Application crashes on 64bit architecture
"Somehow" LessTif does still have problems to work properly
on 64bit platforms, e.g. those based on the alpha processor.
There's not a simple known work-around, but we are working to get this
fixed! As of releases above 0.92.26 we hope to iron out another
category of crashes. We're convinced that we will soon provide the same
quality as on 32bit platforms!
Actually most LessTif widgets work somewhat.
Many work fairly well.
Things like traversal and focus handling have been worked on,
but probably aren't really all that functional yet.
The menu system is quickly losing its child diseases
(occasionally freezing the X server with grabs).
If you're not in a rush when working the menus,
the odds are low that you'll get in much trouble.
Also dragging in the menus will get you in trouble faster
than clicking.
In short, if something does not work quite right,
send us an
email
and we'll try to help you as soon as we possibly can!
In fact telling us about your problem is the fastest way to
get your app to work with LessTif. Recommended !
How often is a release made ?
Starting December 1996 we plan to make intermediary releases every
month or so, and "real" releases every three months or so.
The 0.75 release was made available around December 11, 1996.
In April 2000 0.90 was released. See
versions.html for a list
of all released versions.
release-policy.html
has more on this topic.
In between releases, you can always grab get our latest
development sources from our
CVS repository.
What if I find a Bug ?
Bug reports are very welcome, and we'll do our best to get
the fixes out as quick as possible.
The web site
and all distributions contain a
write-up
on how to submit bug fixes or reports.
This was not easy though.
The _Xm* functions seem to be undocumented in Motif 1.2 therefore
we will make every effort to implement the functions as best we can.
One of our sources of information was
"Writing Your Own OSF/MOTIF Widgets" by McMinds and Whitty,
kindly donated to us by Linux International.
Many of the _Xm* functions are exposed in
OSF/Motif® 2.0/2.1 where they changed names into Xme*.
Does LessTif support I18N?
Two widgets that accept text input (namely XmText and XmTextField)
do support it, but they don't feature multibyte support.
The XmText and XmTextField widgets can handle input methods, as
described above, but they don't have multibyte support.
This means that Asian input methods which work with a multi-byte
representation of a character will not work (yet).
The XmIm*() API is work in progress,
this is probably not a problem for you as we have yet to
discover an application that uses it.
What about memory leaks ?
Obviously we don't like memory leaks in LessTif.
A couple of tests have been done with commercial memory analysis tools,
some of the apps in the tests/ tree help tracking some leaks as well.
We believe we're not doing really bad.
In fact we did run some simple comparisons with official Motif 1.2.4
implementations which showed LessTif was even leaking less memory!
One package which can help you (and us) in tracking memory problems
both in your application and in LessTif, is dmalloc,
a library which can be obtained from
dmalloc.com .
You can compile LessTif itself with dmalloc by using the
--with-dmalloc option to the "configure" command.
Dmalloc is freely available software, but please note the license
which is different from most other free software licenses.
How to debug LessTif applications ?
We have some documents which should help to track down bugs
in LessTif-based applications.
BUG-HUNTING.html
describes some specifics of LessTif's built-in debugging
facilities while bugs.html covers
more general the topic of debugging X11 applications.
I installed LessTif but I can't compile apps with it. What's wrong ?
You may have an application that's not error-free; or (more likely) one which
needs configuration for your site, computer platform, etc.
It would be a good idea to consult the compilation and installation
guidelines for that application.
If it's not a bug within the application it probably has to do with your
compiler options. If it's indeed that, there are several possibilities.
In the examples we'll give now, we'll be using some installation directories
that may differ from your installation. Please adjust your compilation
parameters accordingly, don't try to fix your installation so it matches
our examples. In our examples, X has been installed in /usr/X11R6 and
LessTif has been installed in /usr/lesstif.
Compilation of applications is really a two-step process :
compiling all sources to object files
linking the object files together
The compilation phase needs to know where to find include files.
These are files that are referenced in the C (or C++) sources of your
programs as
#include <Xm/Xm.h>
and you should find them on your system in a couple of directories
under /usr/lesstif/Motif1.2/include or
/usr/lesstif/Motif2.0/include.
Specifically the file mentioned above should show up as
/usr/lesstif/Motif1.2/include/Xm/Xm.h or
/usr/lesstif/Motif2.0/include/Xm/Xm.h
For your compiler to find these files, it needs to be told where to look.
Using the examples above, the flag needed would be -I/usr/lesstif/include .
Note that you need to tell the compiler the same thing about the X Window System
include files, you need to do that by using the -I/usr/X11R6/include flag.
So together this gives
-I/usr/X11R6/include -I/usr/lesstif/include
The second step, linking all the source files together, requires similar flags
which are shown
below.
My application doesn't build. What do I do ?
If your application doesn't build, this could have several reasons.
Some are discussed for the question
"I installed LessTif but I can't compile apps with it. What's wrong ?"!
If the linking process fails, this probably means you didn't specify some library,
or the required libraries aren't present on your system.
Error messages indicating this are a long list of undefined symbols
most of which have a name with an identical prefix, such as Xm.
The linker needs to know where the libraries are, and additionally you need
to tell it which libraries to include in the link process.
Using the example outlined
above,
we'd need to use the flags
-L/usr/X11R6/lib -L/usr/lesstif/lib
for the linker to know where to look, and
-lXm -lXt -lX11
to know which libraries to use.
In this quite simplified example
you might get away with using those linker flags:
Note that the order of the libraries is usually important (see below),
so try to do it right from the beginning!
We didn't list additional libraries which are often required.
e.g. our Motif® 2.1 compatible libXm requires an additional
-lXp -lXext. Therefore we list some prefixes and the related library,
so you can check which library you are missing.
Prefix
Linker Command
Xt
-lXt
Xmu
-lXmu
Sm
-lSM
Ice
-lICE
Xp
-lXp
Xdbe, Xext, XShape
-lXext
Xm
-lXm
Mrm
-lMrm
Dt
-lDtPrint
The order in which you should specify these options is
Of course not all of these libraries are always necessary,
but in some cases even more libraries may be required
(-lsocket is another candidate here). Also make sure the linker
is able to find the libs, e.g. it may be necessary to add
an -L/usr/lesstif/lib or similar.
Once more, the compilation and installation guidelines for the application
probably tell you which libraries to link with.
Finally, please make sure that you have the X development packages
installed on your system, not only the X "user stuff".
Forgetting to install the development system could result in
messages like Xm/Xm.h : cannot open file,
or -lXt: library not found.
This app uses Imake but it won't build right. Imake is a tool which is included in the
X Window System distributions.
It is an extra layer above Makefiles (processed by the make program)
which attempts to make the build process more system independent.
(Nowadays more and more applications use GNU autoconf and GNU automake
for the same purpose.)
The imake program process an Imakefile and turns it into a Makefile.
Often the Imakefile uses some template file that comes with the application,
to specify additional options.
If you use imake directly to create the Makefile, then this will probably
not work right, because you need to tell imake to read the LessTif
configuration files. The mxmkmf program calls imake with the right
parameters, so just using this should help.
It is also possible that the Imakefile file or some file used by it
overrides some of LessTif's parameters.
Please check whether EXTRA_INCLUDES, XMLIB, or XmClientLibs
are overruled in these files.
If they are, then this is probably the cause of the problem.
Can I use LessTif with C++ ?
You sure can.
There really are two ways.
You can use it directly, or through one of the C++ wrappers for Motif.
Much of this is discussed in the Motif FAQ which can be found
at Ken Lee's website at
http://www.rahul.net/~kenton
We're copying a tiny bit of information from one of the FAQ issues here.
Using LessTif directly with C++ prompts the question on how to use
class member functions as callbacks. Here's part of Ken's answer :
There are three common user problems with C++ callbacks.
First, make sure you use the correct function prototype for
the function declarations.
Second, the callback function must be declared as a static member of the
class.
Third, when registering it with XtAddCallback(), you must use its full
signature.
Note that the "this" pointer is used as the client data.
This technique is popular, but not required.
Motif++ is one of the C++ wrappers for Motif/LessTif.
It has a nice tutorial summarizing mechanisms.
(used to be available from
ftp://src.doc.ic.ac.uk/packages/motif++/, but this link is
dead nowadyays. Try ftp-search on it!)
What about static libraries?
Well, there is (almost) no demand for static libraries so far.
If you want them anyway and are capable to deal with the problems as described
in the in question above, then you may retrieve the
set of
Makefiles for OS/2
and build them on your own.
Why don't statically linked apps work?
You need to call _LtXmFixupVendorShell() at the beginning
of main(), or at least before accessing the LessTif library
somehow. Note that this call was not always exported from earlier
versions of the Xm*.dlls. It does and will always exist from
version 0.92.26 and above.
For further technical details check out the source code in
lib/Xm/Vendor.c
and read the answer to
"Application fails to start".
What about "legacy" applications?
Old LessTif programs may still be linked against Xm.dll while
all recent ones should be linked against the libraries following the
new naming scheme,
i.e. Xm_12.dll, Mrm_20.dll, etc.
For this legacy stuff there was a "final" version of the Motif 1.2
compatible
Xm.dll
being made available as of LessTif version 0.91.8 (August 2000). This is
obviously quite outdated nowadays.
If you really need a more up-to-date library Xm.dll
either try the quick approach of renaming the dll or patching the executable
(both approahces are not really recommended) or built one from scratch.
In fact you just need to simply tweak the linker definition file
(Xm.def here) and the according Makefile.