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The Tk Toolkit
SCCS: @(#) README 1.8 98/08/06 15:51:57
1. Introduction
This directory and its descendants contain the sources and documentation
for Tk, an X11 toolkit implemented with the Tcl scripting language. The
information here corresponds to Tk 8.0.3, which is the third patch update
for Tk 8.0. This release is designed to work with Tcl 8.0.3 and may not
work with any other version of Tcl.
Tk 8.0 is a major release with significant new features such as native
look and feel on Macintoshes and PCs, a new font mechanism, application
embedding, and proper support for Safe-Tcl. See below for details.
There should be no backward incompatibilities in Tk 8.0 that affect
scripts. This patch release fixes various bugs in Tk 8.0; there are no
feature changes relative to Tk 8.0.
Note: with Tk 8.0 the Tk version number skipped from 4.2 to 8.0. The
jump was made in order to synchronize the Tcl and Tk version numbers.
2. Documentation
The best way to get started with Tk is to read one of the introductory
books on Tcl and Tk:
Practical Programming in Tcl and Tk, 2nd Edition, by Brent Welch,
Prentice-Hall, 1997, ISBN 0-13-616830-2
Tcl and the Tk Toolkit, by John Ousterhout,
Addison-Wesley, 1994, ISBN 0-201-63337-X
Exploring Expect, by Don Libes,
O'Reilly and Associates, 1995, ISBN 1-56592-090-2
Other books are listed at
The "doc" subdirectory in this release contains a complete set of
reference manual entries for Tk. Files with extension ".1" are for
programs such as wish; files with extension ".3" are for C library
procedures; and files with extension ".n" describe Tcl commands. To
print any of the manual entries, cd to the "doc" directory and invoke
your favorite variant of troff using the normal -man macros, for example
ditroff -man wish.1
to print wish.1. If Tk has been installed correctly and your "man"
program supports it, you should be able to access the Tcl manual entries
using the normal "man" mechanisms, such as
man wish
If you are porting Tk 3.6 scripts to Tk 4.0 or later releases, you may
find the Postscript file doc/ useful. It is a porting guide
that summarizes the new features and discusses how to deal with the
changes in Tk 4.0 that are not backwards compatible.
There is also an official home for Tcl and Tk on the Web:
These Web pages include release updates, reports on bug fixes and porting
issues, HTML versions of the manual pages, and pointers to many other
Tcl/Tk Web pages at other sites. Check them out!
3. Compiling and installing Tk
This release contains everything you should need to compile and run
Tk under UNIX, Macintoshes, and PCs (either Windows NT, Windows 95,
or Windows 98.)
Before trying to compile Tk you should do the following things:
(a) Check for a binary release. Pre-compiled binary releases are
available now for PCs and Macintoshes, and several flavors of
UNIX. Binary releases are much easier to install than source
releases. To find out whether a binary release is available for
your platform, check the home page for Tcl/Tk
( and also check in the FTP
directory from which you retrieved the base distribution.
(b) Make sure you have the most recent patch release. Look in the
FTP directory from which you retrieved this distribution to see
if it has been updated with patches. Patch releases fix bugs
without changing any features, so you should normally use the
latest patch release for the version of Tk that you want.
Patch releases are available in two forms. A file like
tk8.0p1.tar.Z is a complete release for patch level 1 of Tk
version 8.0. If there is a file with a higher patch level than
this release, just fetch the file with the highest patch level
and use it.
Patches are also available in the form of patch files that just
contain the changes from one patch level to another. These
files have names like tk8.0p1.patch, tk8.0p2.patch, etc. They
may also have .gz or .Z extensions to indicate compression. To
use one of these files, you apply it to an existing release with
the "patch" program. Patches must be applied in order:
tk8.0p1.patch must be applied to an unpatched Tk 8.0 release
to produce a Tk 8.0p1 release; tk8.0p2.patch can then be
applied to Tk 8.0p1 to produce Tk 8.0p2, and so on. To apply an
uncompressed patch file such as tk8.0p1.patch, invoke a shell
command like the following from the directory containing this
file (you may need to replace "patch -p" with "patch -p0"
depending on your version of the patch program):
patch -p < tk8.0p1.patch
If the patch file has a .gz extension, it was compressed with
gzip. To apply it, invoke a command like the following:
gunzip -c tk8.0p1.patch.gz | patch -p
If the patch file has a .Z extension, it was compressed with
compress. To apply it, invoke a command like the following:
zcat tk8.0p1.patch.Z | patch -p
If you're applying a patch to a release that has already been
compiled, then before applying the patch you should cd to the
"unix" subdirectory and type "make distclean" to restore the
directory to a pristine state.
Once you've done this, change to the "unix" subdirectory if you're
compiling under UNIX, "win" if you're compiling under Windows, or
"mac" if you're compiling on a Macintosh. Then follow the instructions
in the README file in that directory for compiling Tk, installing it,
and running the test suite.
4. Getting started
The best way to get started with Tk is by reading one of the introductory
The subdirectory library/demos contains a number of pre-canned scripts
that demonstrate various features of Tk. See the README file in the
directory for a description of what's available. The file
library/demos/widget is a script that you can use to invoke many individual
demonstrations of Tk's facilities, see the code that produced the demos,
and modify the code to try out alternatives.
5. Summary of changes in Tk 8.0
Here is a list of the most important new features in Tk 8.0. The
release also includes several smaller feature changes and bug fixes.
See the "changes" file for a complete list of all changes.
1. Native look and feel. The widgets have been rewritten to provide
(nearly?) native look and feel on the Macintosh and PC. Many
widgets, including scrollbars, menus, and the button family, are
implemented with native platform widgets. Others, such as entries
and texts, have been modified to emulate native look and feel.
These changes are backwards compatible except that (a) some
configuration options are now ignored on some platforms and (b) you
must use the new menu mechanism described below to native look and
feel for menus.
2. There is a new interface for creating menus, where a menubar is
implemented as a menu widget instead of a frame containing menubuttons.
The -menu option for a toplevel is used to specify the name of the
menubar; the menu will be displayed *outside* the toplevel using
different mechanisms on each platform (e.g. on the Macintosh the menu
will appear at the top of the screen). See the menu demos in the
widget demo for examples. The old style of menu still works, but
does not provide native look and feel. Menus have several new
- New "-columnbreak" and "-hideMargin" options make it possible
to create multi-column menus.
- It is now possible to manipulate the Apple and Help menus on
the Macintosh, and the system menu on Windows. It is also
possible to have a right justified Help menu on Unix.
- Menus now issue the virtual event <<MenuSelect>> whenever the
current item changes. Applications can use this to generate
help messages.
- There is a new "-direction" option for menubuttons, which
controls where the menu pops up revenues to the button.
3. The font mechanism in Tk has been completely reworked:
- Font names need not be nasty X LFDs: more intuitive names
like {Times 12 Bold} can also be used. See the manual entry
font.n for details.
- Font requests always succeed now. If the requested font is
not available, Tk finds the closest available font and uses
that one.
- Tk now supports named fonts whose precise attributes can be
changed dynamically. If a named font is changed, any widget
using that font updates itself to reflect the change.
- There is a new command "font" for creating named fonts and
querying various information about fonts.
- There are now officially supported C APIs for measuring and
displaying text. If you use these APIs now, your code will
automatically handle international text when internationalization
is added to Tk in a future release. See the manual entries
MeasureChar.3, TextLayout.3, and FontId.3.
- The old C procedures Tk_GetFontStruct, Tk_NameOfFontStruct,
and Tk_FreeFontStruct have been replaced with more portable
procedures Tk_GetFont, Tk_NameOfFont, and Tk_FreeFont.
4. Application embedding. It is now possible to embedded one Tcl/Tk
application inside another, using the -container option on frame
widgets and the -use option for toplevel widgets or on the command
line for wish. Embedding should be fully functional under Unix,
but the implementation is incomplete on the Macintosh and PC.
5. Tk now works correctly with Safe-Tcl: it can be loaded into
safe interpreters using safe::loadTk.
6. Text widgets now allow images to be embedded directly in the
text without using embedded windows. This is more efficient and
provides smoother scrolling.
7. Buttons have a new -default option for drawing default rings in
a platform-specific manner.
8. There is a new "gray75" bitmap, and the "gray25" bitmap is now
really 25% on (due to an ancient mistake, it had been only 12% on).
The Macintosh now supports native bitmaps, including new builtin
bitmaps "stop", "caution", and "note", plus the ability to use
bitmaps in the application's resource fork.
9. The "destroy" command now ignores windows that don't exist
instead of generating an error.
Tk 8.0 introduces the following incompatibilities that may affect Tcl/Tk
scripts that worked under Tk 4.2 and earlier releases:
1. Font specifications such as "Times 12" now interpret the size
as points, whereas it used to be pixels (this was actually a bug,
since the behavior was documented as points). To get pixels now,
use a negative size such as "Times -12".
2. The -transient option for menus is no longer supported. You can
achieve the same effect with the -type field.
3. In the canvas "coords" command, polygons now return only the
points that were explicitly specified when the polygon was created
(they used to return an extra point if the polygon wasn't originally
closed). Internally, polygons are still closed automatically for
purposes of display and hit detection; the extra point just isn't
returned by the "coords" command.
4. The photo image mechanism now uses Tcl_Channels instead of FILEs,
in order to make it portable. FILEs are no longer used anywhere
in Tk. The procedure Tk_FindPhoto now requires an extra "interp"
argument in order to fix a bug where images in different interpreters
with the same name could get confused.
5. The procedures Tk_GetFontStruct, Tk_NameOfFontStruct,
and Tk_FreeFontStruct have been removed.
Note: the new compiler in Tcl 8.0 may also affect Tcl/Tk scripts; check
the Tcl documentation for information on incompatibilities introduced by
Tcl 8.0.
6. Tcl/Tk newsgroup
There is a network news group "comp.lang.tcl" intended for the exchange
of information about Tcl, Tk, and related applications. Feel free to use
this newsgroup both for general information questions and for bug reports.
We read the newsgroup and will attempt to fix bugs and problems reported
to it.
When using comp.lang.tcl, please be sure that your e-mail return address
is correctly set in your postings. This allows people to respond directly
to you, rather than the entire newsgroup, for answers that are not of
general interest. A bad e-mail return address may prevent you from
getting answers to your questions. You may have to reconfigure your news
reading software to ensure that it is supplying valid e-mail addresses.
7. Mailing lists
A couple of Mailing List have been set up to discuss Macintosh or
Windows related Tcl issues. In order to use these Mailing Lists you
must have access to the internet. To subscribe send a message to:
In the body of the message (the subject will be ignored) put:
subscribe mactcl Joe Blow
Replacing Joe Blow with your real name, of course. (Use wintcl
instead of mactcl if your interested in the Windows list.) If you
would just like to receive more information about the list without
subscribing but the line:
information mactcl
in the body instead (or wintcl).
8. Tcl/Tk contributed archive
Many people have created exciting packages and applications based on Tcl
and/or Tk and made them freely available to the Tcl community. An archive
of these contributions is kept on the machine You
can access the archive using anonymous FTP; the Tcl contributed archive is
in the directory "/pub/tcl". The archive also contains several FAQ
("frequently asked questions") documents that provide solutions to problems
that are commonly encountered by TCL newcomers.
9. Tcl Resource Center
Visit to see an annotated index of
many Tcl resources available on the World Wide Web. This includes
papers, books, and FAQs, as well as extensions, applications, binary
releases, and patches. You can contribute patches by sending them
to <>. You can also recommend more URLs for the
resource center using the forms labeled "Add a Resource".
10. Support and bug fixes
We're very interested in receiving bug reports and suggestions for
improvements. We prefer that you send this information to the
comp.lang.tcl newsgroup rather than to any of us at Scriptics. We'll see
anything on comp.lang.tcl, and in addition someone else who reads
comp.lang.tcl may be able to offer a solution. The normal turn-around
time for bugs is 3-6 weeks. Enhancements may take longer and may not
happen at all unless there is widespread support for them (we're
trying to slow the rate at which Tk turns into a kitchen sink). It's
very difficult to make incompatible changes to Tcl at this point, due
to the size of the installed base.
When reporting bugs, please provide a short wish script that we can
use to reproduce the bug. Make sure that the script runs with a
bare-bones wish and doesn't depend on any extensions or other
programs, particularly those that exist only at your site. Also,
please include three additional pieces of information with the
(a) how do we use the script to make the problem happen (e.g.
what things do we click on, in what order)?
(b) what happens when you do these things (presumably this is
(c) what did you expect to happen instead?
The Tcl/Tk community is too large for us to provide much individual
support for users. If you need help we suggest that you post questions
to comp.lang.tcl. We read the newsgroup and will attempt to answer
esoteric questions for which no-one else is likely to know the answer.
In addition, Tcl/Tk support and training are available commercially from
Scriptics (, NeoSoft (,
Computerized Processes Unlimited (,
and Data Kinetics (
11. Release organization
The version numbers described below are available to Tcl scripts
as the tk_version and tk_patchLevel Tcl variables.
Each Tk release is identified by two numbers separated by a dot, e.g.
3.2 or 3.3. If a new release contains changes that are likely to break
existing C code or Tcl scripts then the major release number increments
and the minor number resets to zero: 3.0, 4.0, etc. If a new release
contains only bug fixes and compatible changes, then the minor number
increments without changing the major number, e.g. 3.1, 3.2, etc. If
you have C code or Tcl scripts that work with release X.Y, then they
should also work with any release X.Z as long as Z > Y.
Alpha and beta releases have an additional suffix of the form a2 or b1.
For example, Tk 3.3b1 is the first beta release of Tk version 3.3,
Tk 3.3b2 is the second beta release, and so on. A beta release is an
initial version of a new release, used to fix bugs and bad features
before declaring the release stable. An alpha release is like a beta
release, except it's likely to need even more work before it's "ready
for prime time". New releases are normally preceded by one or more
alpha and beta releases. We hope that lots of people will try out
the alpha and beta releases and report problems. We'll make new alpha/
beta releases to fix the problems, until eventually there is a beta
release that appears to be stable. Once this occurs we'll make the
final release.
We can't promise to maintain compatibility among alpha and beta releases.
For example, release 4.1b2 may not be backward compatible with 4.1b1, even
though the final 4.1 release will be backward compatible with 4.0. This
allows us to change new features as we find problems during beta testing.
We'll try to minimize incompatibilities between beta releases, but if a
major problem turns up then we'll fix it even if it introduces an
incompatibility. Once the official release is made then there won't
be any more incompatibilities until the next release with a new major
version number.
Patch releases used to have a suffix such as p1 or p2. Now we use
a 3-part version number: major.minor.patchlevel. (e.g., 8.0.3)
These releases contain bug fixes only. A patch release (e.g Tk 4.1p2)
should be completely compatible with the base release from which it is
derived (e.g. Tk 4.1), and you should normally use the highest available
patch release.