cpython/Doc/library/tkinter.rst

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:mod:`tkinter` --- Python interface to Tcl/Tk
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=============================================
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.. module:: tkinter
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:synopsis: Interface to Tcl/Tk for graphical user interfaces
.. moduleauthor:: Guido van Rossum <guido@Python.org>
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The :mod:`tkinter` package ("Tk interface") is the standard Python interface to
the Tk GUI toolkit. Both Tk and :mod:`tkinter` are available on most Unix
platforms, as well as on Windows systems. (Tk itself is not part of Python; it
is maintained at ActiveState.) You can check that :mod:`tkinter` is properly
installed on your system by running ``python -m tkinter`` from the command line;
this should open a window demonstrating a simple Tk interface.
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.. seealso::
`Python Tkinter Resources <http://www.python.org/topics/tkinter/>`_
The Python Tkinter Topic Guide provides a great deal of information on using Tk
from Python and links to other sources of information on Tk.
`An Introduction to Tkinter <http://www.pythonware.com/library/an-introduction-to-tkinter.htm>`_
Fredrik Lundh's on-line reference material.
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Patch from Trent Nelson. Also simplified removing a file by using test_support. ........ r61242 | neal.norwitz | 2008-03-05 06:14:18 +0100 (Wed, 05 Mar 2008) | 3 lines Get this test to pass even when there is no sound card in the system. Patch from Trent Nelson. (I can't test this.) ........ r61243 | neal.norwitz | 2008-03-05 06:20:44 +0100 (Wed, 05 Mar 2008) | 3 lines Catch OSError when trying to remove a file in case removal fails. This should prevent a failure in tearDown masking any real test failure. ........ r61244 | neal.norwitz | 2008-03-05 06:38:06 +0100 (Wed, 05 Mar 2008) | 5 lines Make the timeout longer to give slow machines a chance to pass the test before timing out. This doesn't change the duration of the test under normal circumstances. This is targetted at fixing the spurious failures on the FreeBSD buildbot primarily. ........ r61245 | neal.norwitz | 2008-03-05 06:49:03 +0100 (Wed, 05 Mar 2008) | 1 line Tabs -> spaces ........ r61246 | neal.norwitz | 2008-03-05 06:50:20 +0100 (Wed, 05 Mar 2008) | 1 line Use -u urlfetch to run more tests ........ r61247 | neal.norwitz | 2008-03-05 06:51:20 +0100 (Wed, 05 Mar 2008) | 1 line test_smtplib sometimes reports leaks too, suppress it ........ r61248 | jeffrey.yasskin | 2008-03-05 07:19:56 +0100 (Wed, 05 Mar 2008) | 5 lines Fix test_socketserver on Windows after r61099 added several signal.alarm() calls (which don't exist on non-Unix platforms). Thanks to Trent Nelson for the report and patch. ........ r61249 | georg.brandl | 2008-03-05 08:10:35 +0100 (Wed, 05 Mar 2008) | 2 lines Fix some rst. ........ r61252 | thomas.heller | 2008-03-05 15:53:39 +0100 (Wed, 05 Mar 2008) | 2 lines News entry for yesterdays commit. ........ r61253 | thomas.heller | 2008-03-05 16:34:29 +0100 (Wed, 05 Mar 2008) | 3 lines Issue 1872: Changed the struct module typecode from 't' to '?', for compatibility with PEP3118. ........ r61254 | skip.montanaro | 2008-03-05 17:41:09 +0100 (Wed, 05 Mar 2008) | 4 lines Elaborate on the role of the altinstall target when installing multiple versions. ........ r61255 | georg.brandl | 2008-03-05 20:31:44 +0100 (Wed, 05 Mar 2008) | 2 lines #2239: PYTHONPATH delimiter is os.pathsep. ........ r61256 | raymond.hettinger | 2008-03-05 21:59:58 +0100 (Wed, 05 Mar 2008) | 1 line C implementation of itertools.permutations(). ........ r61257 | raymond.hettinger | 2008-03-05 22:04:32 +0100 (Wed, 05 Mar 2008) | 1 line Small code cleanup. ........ r61260 | martin.v.loewis | 2008-03-05 23:24:31 +0100 (Wed, 05 Mar 2008) | 2 lines cd PCbuild only after deleting all pyc files. ........ r61261 | raymond.hettinger | 2008-03-06 02:15:52 +0100 (Thu, 06 Mar 2008) | 1 line Add examples. ........ r61262 | andrew.kuchling | 2008-03-06 02:36:27 +0100 (Thu, 06 Mar 2008) | 1 line Add two items ........ r61263 | georg.brandl | 2008-03-06 07:47:18 +0100 (Thu, 06 Mar 2008) | 2 lines #1725737: ignore other VC directories other than CVS and SVN's too. ........ r61264 | martin.v.loewis | 2008-03-06 07:55:22 +0100 (Thu, 06 Mar 2008) | 4 lines Patch #2232: os.tmpfile might fail on Windows if the user has no permission to create files in the root directory. Will backport to 2.5. ........ r61269 | georg.brandl | 2008-03-06 08:19:15 +0100 (Thu, 06 Mar 2008) | 2 lines Expand on re.split behavior with captured expressions. ........ r61270 | georg.brandl | 2008-03-06 08:22:09 +0100 (Thu, 06 Mar 2008) | 2 lines Little clarification of assignments. ........ r61271 | georg.brandl | 2008-03-06 08:31:34 +0100 (Thu, 06 Mar 2008) | 2 lines Add isinstance/issubclass to tutorial. ........ r61272 | georg.brandl | 2008-03-06 08:34:52 +0100 (Thu, 06 Mar 2008) | 2 lines Add missing NEWS entry for r61263. ........ r61273 | georg.brandl | 2008-03-06 08:41:16 +0100 (Thu, 06 Mar 2008) | 2 lines #2225: return nonzero status code from py_compile if not all files could be compiled. ........ r61274 | georg.brandl | 2008-03-06 08:43:02 +0100 (Thu, 06 Mar 2008) | 2 lines #2220: handle matching failure more gracefully. ........ r61275 | georg.brandl | 2008-03-06 08:45:52 +0100 (Thu, 06 Mar 2008) | 2 lines Bug #2220: handle rlcompleter attribute match failure more gracefully. ........ r61278 | martin.v.loewis | 2008-03-06 14:49:47 +0100 (Thu, 06 Mar 2008) | 1 line Rely on x64 platform configuration when building _bsddb on AMD64. ........ r61279 | martin.v.loewis | 2008-03-06 14:50:28 +0100 (Thu, 06 Mar 2008) | 1 line Update db-4.4.20 build procedure. ........ r61285 | raymond.hettinger | 2008-03-06 21:52:01 +0100 (Thu, 06 Mar 2008) | 1 line More tests. ........ r61286 | raymond.hettinger | 2008-03-06 23:51:36 +0100 (Thu, 06 Mar 2008) | 1 line Issue 2246: itertools grouper object did not participate in GC (should be backported). ........ r61288 | raymond.hettinger | 2008-03-07 02:33:20 +0100 (Fri, 07 Mar 2008) | 1 line Tweak recipes and tests ........ r61289 | jeffrey.yasskin | 2008-03-07 07:22:15 +0100 (Fri, 07 Mar 2008) | 5 lines Progress on issue #1193577 by adding a polling .shutdown() method to SocketServers. The core of the patch was written by Pedro Werneck, but any bugs are mine. I've also rearranged the code for timeouts in order to avoid interfering with the shutdown poll. ........ r61290 | nick.coghlan | 2008-03-07 15:13:28 +0100 (Fri, 07 Mar 2008) | 1 line Speed up with statements by storing the __exit__ method on the stack instead of in a temp variable (bumps the magic number for pyc files) ........ r61298 | andrew.kuchling | 2008-03-07 22:09:23 +0100 (Fri, 07 Mar 2008) | 1 line Grammar fix ........ r61303 | georg.brandl | 2008-03-08 10:54:06 +0100 (Sat, 08 Mar 2008) | 2 lines #2253: fix continue vs. finally docs. ........ r61304 | marc-andre.lemburg | 2008-03-08 11:01:43 +0100 (Sat, 08 Mar 2008) | 3 lines Add new name for Mandrake: Mandriva. ........ r61305 | georg.brandl | 2008-03-08 11:05:24 +0100 (Sat, 08 Mar 2008) | 2 lines #1533486: fix types in refcount intro. ........ r61312 | facundo.batista | 2008-03-08 17:50:27 +0100 (Sat, 08 Mar 2008) | 5 lines Issue 1106316. post_mortem()'s parameter, traceback, is now optional: it defaults to the traceback of the exception that is currently being handled. ........ r61313 | jeffrey.yasskin | 2008-03-08 19:26:54 +0100 (Sat, 08 Mar 2008) | 2 lines Add tests for with and finally performance to pybench. ........ r61314 | jeffrey.yasskin | 2008-03-08 21:08:21 +0100 (Sat, 08 Mar 2008) | 2 lines Fix pybench for pythons < 2.6, tested back to 2.3. ........ r61317 | jeffrey.yasskin | 2008-03-08 22:35:15 +0100 (Sat, 08 Mar 2008) | 3 lines Well that was dumb. platform.python_implementation returns a function, not a string. ........ r61329 | georg.brandl | 2008-03-09 16:11:39 +0100 (Sun, 09 Mar 2008) | 2 lines #2249: document assertTrue and assertFalse. ........ r61332 | neal.norwitz | 2008-03-09 20:03:42 +0100 (Sun, 09 Mar 2008) | 4 lines Introduce a lock to fix a race condition which caused an exception in the test. Some buildbots were consistently failing (e.g., amd64). Also remove a couple of semi-colons. ........ r61344 | raymond.hettinger | 2008-03-11 01:19:07 +0100 (Tue, 11 Mar 2008) | 1 line Add recipe to docs. ........ r61350 | guido.van.rossum | 2008-03-11 22:18:06 +0100 (Tue, 11 Mar 2008) | 3 lines Fix the overflows in expandtabs(). "This time for sure!" (Exploit at request.) ........ r61351 | raymond.hettinger | 2008-03-11 22:37:46 +0100 (Tue, 11 Mar 2008) | 1 line Improve docs for itemgetter(). Show that it works with slices. ........ r61363 | georg.brandl | 2008-03-13 08:15:56 +0100 (Thu, 13 Mar 2008) | 2 lines #2265: fix example. ........ r61364 | georg.brandl | 2008-03-13 08:17:14 +0100 (Thu, 13 Mar 2008) | 2 lines #2270: fix typo. ........ r61365 | georg.brandl | 2008-03-13 08:21:41 +0100 (Thu, 13 Mar 2008) | 2 lines #1720705: add docs about import/threading interaction, wording by Nick. ........ r61366 | andrew.kuchling | 2008-03-13 12:07:35 +0100 (Thu, 13 Mar 2008) | 1 line Add class decorators ........ r61367 | raymond.hettinger | 2008-03-13 17:43:17 +0100 (Thu, 13 Mar 2008) | 1 line Add 2-to-3 support for the itertools moved to builtins or renamed. ........ r61368 | raymond.hettinger | 2008-03-13 17:43:59 +0100 (Thu, 13 Mar 2008) | 1 line Consistent tense. ........ r61369 | raymond.hettinger | 2008-03-13 20:03:51 +0100 (Thu, 13 Mar 2008) | 1 line Issue 2274: Add heapq.heappushpop(). ........ r61370 | raymond.hettinger | 2008-03-13 20:33:34 +0100 (Thu, 13 Mar 2008) | 1 line Simplify the nlargest() code using heappushpop(). ........ r61371 | brett.cannon | 2008-03-13 21:27:00 +0100 (Thu, 13 Mar 2008) | 4 lines Move test_thread over to unittest. Commits GHOP 237. Thanks Benjamin Peterson for the patch. ........ r61372 | brett.cannon | 2008-03-13 21:33:10 +0100 (Thu, 13 Mar 2008) | 4 lines Move test_tokenize to doctest. Done as GHOP 238 by Josip Dzolonga. ........ r61373 | brett.cannon | 2008-03-13 21:47:41 +0100 (Thu, 13 Mar 2008) | 4 lines Convert test_contains, test_crypt, and test_select to unittest. Patch from GHOP 294 by David Marek. ........ r61374 | brett.cannon | 2008-03-13 22:02:16 +0100 (Thu, 13 Mar 2008) | 4 lines Move test_gdbm to use unittest. Closes issue #1960. Thanks Giampaolo Rodola. ........ r61375 | brett.cannon | 2008-03-13 22:09:28 +0100 (Thu, 13 Mar 2008) | 4 lines Convert test_fcntl to unittest. Closes issue #2055. Thanks Giampaolo Rodola. ........ r61376 | raymond.hettinger | 2008-03-14 06:03:44 +0100 (Fri, 14 Mar 2008) | 1 line Leave heapreplace() unchanged. ........ r61378 | martin.v.loewis | 2008-03-14 14:56:09 +0100 (Fri, 14 Mar 2008) | 2 lines Patch #2284: add -x64 option to rt.bat. ........ r61379 | martin.v.loewis | 2008-03-14 14:57:59 +0100 (Fri, 14 Mar 2008) | 2 lines Use -x64 flag. ........ r61382 | brett.cannon | 2008-03-14 15:03:10 +0100 (Fri, 14 Mar 2008) | 2 lines Remove a bad test. ........ r61383 | mark.dickinson | 2008-03-14 15:23:37 +0100 (Fri, 14 Mar 2008) | 9 lines Issue 705836: Fix struct.pack(">f", 1e40) to behave consistently across platforms: it should now raise OverflowError on all platforms. (Previously it raised OverflowError only on non IEEE 754 platforms.) Also fix the (already existing) test for this behaviour so that it actually raises TestFailed instead of just referencing it. ........ r61387 | thomas.heller | 2008-03-14 22:06:21 +0100 (Fri, 14 Mar 2008) | 1 line Remove unneeded initializer. ........ r61388 | martin.v.loewis | 2008-03-14 22:19:28 +0100 (Fri, 14 Mar 2008) | 2 lines Run debug version, cd to PCbuild. ........ r61392 | georg.brandl | 2008-03-15 00:10:34 +0100 (Sat, 15 Mar 2008) | 2 lines Remove obsolete paragraph. #2288. ........ r61395 | georg.brandl | 2008-03-15 01:20:19 +0100 (Sat, 15 Mar 2008) | 2 lines Fix lots of broken links in the docs, found by Sphinx' external link checker. ........ r61396 | skip.montanaro | 2008-03-15 03:32:49 +0100 (Sat, 15 Mar 2008) | 1 line note that fork and forkpty raise OSError on failure ........ r61402 | skip.montanaro | 2008-03-15 17:04:45 +0100 (Sat, 15 Mar 2008) | 1 line add %f format to datetime - issue 1158 ........ r61403 | skip.montanaro | 2008-03-15 17:07:11 +0100 (Sat, 15 Mar 2008) | 2 lines . ........
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`Tkinter reference: a GUI for Python <http://infohost.nmt.edu/tcc/help/pubs/lang.html>`_
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On-line reference material.
`Python and Tkinter Programming <http://www.amazon.com/exec/obidos/ASIN/1884777813>`_
The book by John Grayson (ISBN 1-884777-81-3).
Tkinter Modules
---------------
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Most of the time, :mod:`tkinter` is all you really need, but a number of
additional modules are available as well. The Tk interface is located in a
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binary module named :mod:`_tkinter`. This module contains the low-level
interface to Tk, and should never be used directly by application programmers.
It is usually a shared library (or DLL), but might in some cases be statically
linked with the Python interpreter.
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In addition to the Tk interface module, :mod:`tkinter` includes a number of
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Python modules, :mod:`tkinter.constants` being one of the most important.
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Importing :mod:`tkinter` will automatically import :mod:`tkinter.constants`,
so, usually, to use Tkinter all you need is a simple import statement::
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import tkinter
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Or, more often::
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from tkinter import *
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.. class:: Tk(screenName=None, baseName=None, className='Tk', useTk=1)
The :class:`Tk` class is instantiated without arguments. This creates a toplevel
widget of Tk which usually is the main window of an application. Each instance
has its own associated Tcl interpreter.
.. FIXME: The following keyword arguments are currently recognized:
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.. function:: Tcl(screenName=None, baseName=None, className='Tk', useTk=0)
The :func:`Tcl` function is a factory function which creates an object much like
that created by the :class:`Tk` class, except that it does not initialize the Tk
subsystem. This is most often useful when driving the Tcl interpreter in an
environment where one doesn't want to create extraneous toplevel windows, or
where one cannot (such as Unix/Linux systems without an X server). An object
created by the :func:`Tcl` object can have a Toplevel window created (and the Tk
subsystem initialized) by calling its :meth:`loadtk` method.
Other modules that provide Tk support include:
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:mod:`tkinter.scrolledtext`
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Text widget with a vertical scroll bar built in.
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:mod:`tkinter.colorchooser`
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Dialog to let the user choose a color.
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:mod:`tkinter.commondialog`
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Base class for the dialogs defined in the other modules listed here.
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:mod:`tkinter.filedialog`
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Common dialogs to allow the user to specify a file to open or save.
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:mod:`tkinter.font`
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Utilities to help work with fonts.
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:mod:`tkinter.messagebox`
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Access to standard Tk dialog boxes.
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:mod:`tkinter.simpledialog`
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Basic dialogs and convenience functions.
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:mod:`tkinter.dnd`
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Drag-and-drop support for :mod:`tkinter`. This is experimental and should
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become deprecated when it is replaced with the Tk DND.
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:mod:`turtle`
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Turtle graphics in a Tk window.
Tkinter Life Preserver
----------------------
.. sectionauthor:: Matt Conway
This section is not designed to be an exhaustive tutorial on either Tk or
Tkinter. Rather, it is intended as a stop gap, providing some introductory
orientation on the system.
Credits:
* Tk was written by John Ousterhout while at Berkeley.
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* Tkinter was written by Steen Lumholt and Guido van Rossum.
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* This Life Preserver was written by Matt Conway at the University of Virginia.
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* The HTML rendering, and some liberal editing, was produced from a FrameMaker
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version by Ken Manheimer.
* Fredrik Lundh elaborated and revised the class interface descriptions, to get
them current with Tk 4.2.
* Mike Clarkson converted the documentation to LaTeX, and compiled the User
Interface chapter of the reference manual.
How To Use This Section
^^^^^^^^^^^^^^^^^^^^^^^
This section is designed in two parts: the first half (roughly) covers
background material, while the second half can be taken to the keyboard as a
handy reference.
When trying to answer questions of the form "how do I do blah", it is often best
to find out how to do"blah" in straight Tk, and then convert this back into the
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corresponding :mod:`tkinter` call. Python programmers can often guess at the
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correct Python command by looking at the Tk documentation. This means that in
order to use Tkinter, you will have to know a little bit about Tk. This document
can't fulfill that role, so the best we can do is point you to the best
documentation that exists. Here are some hints:
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* The authors strongly suggest getting a copy of the Tk man pages.
Specifically, the man pages in the ``manN`` directory are most useful.
The ``man3`` man pages describe the C interface to the Tk library and thus
are not especially helpful for script writers.
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* Addison-Wesley publishes a book called Tcl and the Tk Toolkit by John
Ousterhout (ISBN 0-201-63337-X) which is a good introduction to Tcl and Tk for
the novice. The book is not exhaustive, and for many details it defers to the
man pages.
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* :file:`tkinter/__init__.py` is a last resort for most, but can be a good
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place to go when nothing else makes sense.
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.. seealso::
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`Tcl/Tk 8.6 man pages <http://www.tcl.tk/man/tcl8.6/>`_
The Tcl/Tk manual on www.tcl.tk.
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`ActiveState Tcl Home Page <http://tcl.activestate.com/>`_
The Tk/Tcl development is largely taking place at ActiveState.
`Tcl and the Tk Toolkit <http://www.amazon.com/exec/obidos/ASIN/020163337X>`_
The book by John Ousterhout, the inventor of Tcl .
`Practical Programming in Tcl and Tk <http://www.amazon.com/exec/obidos/ASIN/0130220280>`_
Brent Welch's encyclopedic book.
A Simple Hello World Program
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
::
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from tkinter import *
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class Application(Frame):
def say_hi(self):
print("hi there, everyone!")
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def createWidgets(self):
self.QUIT = Button(self)
self.QUIT["text"] = "QUIT"
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self.QUIT["fg"] = "red"
self.QUIT["command"] = self.quit
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self.QUIT.pack({"side": "left"})
self.hi_there = Button(self)
self.hi_there["text"] = "Hello",
self.hi_there["command"] = self.say_hi
self.hi_there.pack({"side": "left"})
def __init__(self, master=None):
Frame.__init__(self, master)
self.pack()
self.createWidgets()
root = Tk()
app = Application(master=root)
app.mainloop()
root.destroy()
A (Very) Quick Look at Tcl/Tk
-----------------------------
The class hierarchy looks complicated, but in actual practice, application
programmers almost always refer to the classes at the very bottom of the
hierarchy.
Notes:
* These classes are provided for the purposes of organizing certain functions
under one namespace. They aren't meant to be instantiated independently.
* The :class:`Tk` class is meant to be instantiated only once in an application.
Application programmers need not instantiate one explicitly, the system creates
one whenever any of the other classes are instantiated.
* The :class:`Widget` class is not meant to be instantiated, it is meant only
for subclassing to make "real" widgets (in C++, this is called an 'abstract
class').
To make use of this reference material, there will be times when you will need
to know how to read short passages of Tk and how to identify the various parts
of a Tk command. (See section :ref:`tkinter-basic-mapping` for the
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:mod:`tkinter` equivalents of what's below.)
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Tk scripts are Tcl programs. Like all Tcl programs, Tk scripts are just lists
of tokens separated by spaces. A Tk widget is just its *class*, the *options*
that help configure it, and the *actions* that make it do useful things.
To make a widget in Tk, the command is always of the form::
classCommand newPathname options
*classCommand*
denotes which kind of widget to make (a button, a label, a menu...)
*newPathname*
is the new name for this widget. All names in Tk must be unique. To help
enforce this, widgets in Tk are named with *pathnames*, just like files in a
file system. The top level widget, the *root*, is called ``.`` (period) and
children are delimited by more periods. For example,
``.myApp.controlPanel.okButton`` might be the name of a widget.
*options*
configure the widget's appearance and in some cases, its behavior. The options
come in the form of a list of flags and values. Flags are preceded by a '-',
like Unix shell command flags, and values are put in quotes if they are more
than one word.
For example::
button .fred -fg red -text "hi there"
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^ ^ \______________________/
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| | |
class new options
command widget (-opt val -opt val ...)
Once created, the pathname to the widget becomes a new command. This new
*widget command* is the programmer's handle for getting the new widget to
perform some *action*. In C, you'd express this as someAction(fred,
someOptions), in C++, you would express this as fred.someAction(someOptions),
and in Tk, you say::
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.fred someAction someOptions
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Note that the object name, ``.fred``, starts with a dot.
As you'd expect, the legal values for *someAction* will depend on the widget's
class: ``.fred disable`` works if fred is a button (fred gets greyed out), but
does not work if fred is a label (disabling of labels is not supported in Tk).
The legal values of *someOptions* is action dependent. Some actions, like
``disable``, require no arguments, others, like a text-entry box's ``delete``
command, would need arguments to specify what range of text to delete.
.. _tkinter-basic-mapping:
Mapping Basic Tk into Tkinter
-----------------------------
Class commands in Tk correspond to class constructors in Tkinter. ::
button .fred =====> fred = Button()
The master of an object is implicit in the new name given to it at creation
time. In Tkinter, masters are specified explicitly. ::
button .panel.fred =====> fred = Button(panel)
The configuration options in Tk are given in lists of hyphened tags followed by
values. In Tkinter, options are specified as keyword-arguments in the instance
constructor, and keyword-args for configure calls or as instance indices, in
dictionary style, for established instances. See section
:ref:`tkinter-setting-options` on setting options. ::
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button .fred -fg red =====> fred = Button(panel, fg="red")
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.fred configure -fg red =====> fred["fg"] = red
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OR ==> fred.config(fg="red")
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In Tk, to perform an action on a widget, use the widget name as a command, and
follow it with an action name, possibly with arguments (options). In Tkinter,
you call methods on the class instance to invoke actions on the widget. The
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actions (methods) that a given widget can perform are listed in
:file:`tkinter/__init__.py`. ::
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.fred invoke =====> fred.invoke()
To give a widget to the packer (geometry manager), you call pack with optional
arguments. In Tkinter, the Pack class holds all this functionality, and the
various forms of the pack command are implemented as methods. All widgets in
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:mod:`tkinter` are subclassed from the Packer, and so inherit all the packing
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methods. See the :mod:`tkinter.tix` module documentation for additional
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information on the Form geometry manager. ::
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pack .fred -side left =====> fred.pack(side="left")
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How Tk and Tkinter are Related
------------------------------
From the top down:
Your App Here (Python)
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A Python application makes a :mod:`tkinter` call.
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tkinter (Python Package)
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This call (say, for example, creating a button widget), is implemented in
the :mod:`tkinter` package, which is written in Python. This Python
function will parse the commands and the arguments and convert them into a
form that makes them look as if they had come from a Tk script instead of
a Python script.
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_tkinter (C)
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These commands and their arguments will be passed to a C function in the
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:mod:`_tkinter` - note the underscore - extension module.
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Tk Widgets (C and Tcl)
This C function is able to make calls into other C modules, including the C
functions that make up the Tk library. Tk is implemented in C and some Tcl.
The Tcl part of the Tk widgets is used to bind certain default behaviors to
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widgets, and is executed once at the point where the Python :mod:`tkinter`
package is imported. (The user never sees this stage).
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Tk (C)
The Tk part of the Tk Widgets implement the final mapping to ...
Xlib (C)
the Xlib library to draw graphics on the screen.
Handy Reference
---------------
.. _tkinter-setting-options:
Setting Options
^^^^^^^^^^^^^^^
Options control things like the color and border width of a widget. Options can
be set in three ways:
At object creation time, using keyword arguments
::
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fred = Button(self, fg="red", bg="blue")
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After object creation, treating the option name like a dictionary index
::
fred["fg"] = "red"
fred["bg"] = "blue"
Use the config() method to update multiple attrs subsequent to object creation
::
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fred.config(fg="red", bg="blue")
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For a complete explanation of a given option and its behavior, see the Tk man
pages for the widget in question.
Note that the man pages list "STANDARD OPTIONS" and "WIDGET SPECIFIC OPTIONS"
for each widget. The former is a list of options that are common to many
widgets, the latter are the options that are idiosyncratic to that particular
widget. The Standard Options are documented on the :manpage:`options(3)` man
page.
No distinction between standard and widget-specific options is made in this
document. Some options don't apply to some kinds of widgets. Whether a given
widget responds to a particular option depends on the class of the widget;
buttons have a ``command`` option, labels do not.
The options supported by a given widget are listed in that widget's man page, or
can be queried at runtime by calling the :meth:`config` method without
arguments, or by calling the :meth:`keys` method on that widget. The return
value of these calls is a dictionary whose key is the name of the option as a
string (for example, ``'relief'``) and whose values are 5-tuples.
Some options, like ``bg`` are synonyms for common options with long names
(``bg`` is shorthand for "background"). Passing the ``config()`` method the name
of a shorthand option will return a 2-tuple, not 5-tuple. The 2-tuple passed
back will contain the name of the synonym and the "real" option (such as
``('bg', 'background')``).
+-------+---------------------------------+--------------+
| Index | Meaning | Example |
+=======+=================================+==============+
| 0 | option name | ``'relief'`` |
+-------+---------------------------------+--------------+
| 1 | option name for database lookup | ``'relief'`` |
+-------+---------------------------------+--------------+
| 2 | option class for database | ``'Relief'`` |
| | lookup | |
+-------+---------------------------------+--------------+
| 3 | default value | ``'raised'`` |
+-------+---------------------------------+--------------+
| 4 | current value | ``'groove'`` |
+-------+---------------------------------+--------------+
Example::
>>> print(fred.config())
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{'relief' : ('relief', 'relief', 'Relief', 'raised', 'groove')}
Of course, the dictionary printed will include all the options available and
their values. This is meant only as an example.
The Packer
^^^^^^^^^^
.. index:: single: packing (widgets)
The packer is one of Tk's geometry-management mechanisms. Geometry managers
are used to specify the relative positioning of the positioning of widgets
within their container - their mutual *master*. In contrast to the more
cumbersome *placer* (which is used less commonly, and we do not cover here), the
packer takes qualitative relationship specification - *above*, *to the left of*,
*filling*, etc - and works everything out to determine the exact placement
coordinates for you.
The size of any *master* widget is determined by the size of the "slave widgets"
inside. The packer is used to control where slave widgets appear inside the
master into which they are packed. You can pack widgets into frames, and frames
into other frames, in order to achieve the kind of layout you desire.
Additionally, the arrangement is dynamically adjusted to accommodate incremental
changes to the configuration, once it is packed.
Note that widgets do not appear until they have had their geometry specified
with a geometry manager. It's a common early mistake to leave out the geometry
specification, and then be surprised when the widget is created but nothing
appears. A widget will appear only after it has had, for example, the packer's
:meth:`pack` method applied to it.
The pack() method can be called with keyword-option/value pairs that control
where the widget is to appear within its container, and how it is to behave when
the main application window is resized. Here are some examples::
fred.pack() # defaults to side = "top"
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fred.pack(side="left")
fred.pack(expand=1)
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Packer Options
^^^^^^^^^^^^^^
For more extensive information on the packer and the options that it can take,
see the man pages and page 183 of John Ousterhout's book.
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anchor
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Anchor type. Denotes where the packer is to place each slave in its parcel.
expand
Boolean, ``0`` or ``1``.
fill
Legal values: ``'x'``, ``'y'``, ``'both'``, ``'none'``.
ipadx and ipady
A distance - designating internal padding on each side of the slave widget.
padx and pady
A distance - designating external padding on each side of the slave widget.
side
Legal values are: ``'left'``, ``'right'``, ``'top'``, ``'bottom'``.
Coupling Widget Variables
^^^^^^^^^^^^^^^^^^^^^^^^^
The current-value setting of some widgets (like text entry widgets) can be
connected directly to application variables by using special options. These
options are ``variable``, ``textvariable``, ``onvalue``, ``offvalue``, and
``value``. This connection works both ways: if the variable changes for any
reason, the widget it's connected to will be updated to reflect the new value.
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Unfortunately, in the current implementation of :mod:`tkinter` it is not
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possible to hand over an arbitrary Python variable to a widget through a
``variable`` or ``textvariable`` option. The only kinds of variables for which
this works are variables that are subclassed from a class called Variable,
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defined in :mod:`tkinter`.
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There are many useful subclasses of Variable already defined:
:class:`StringVar`, :class:`IntVar`, :class:`DoubleVar`, and
:class:`BooleanVar`. To read the current value of such a variable, call the
:meth:`get` method on it, and to change its value you call the :meth:`!set`
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method. If you follow this protocol, the widget will always track the value of
the variable, with no further intervention on your part.
For example::
class App(Frame):
def __init__(self, master=None):
Frame.__init__(self, master)
self.pack()
self.entrythingy = Entry()
self.entrythingy.pack()
# here is the application variable
self.contents = StringVar()
# set it to some value
self.contents.set("this is a variable")
# tell the entry widget to watch this variable
self.entrythingy["textvariable"] = self.contents
# and here we get a callback when the user hits return.
# we will have the program print out the value of the
# application variable when the user hits return
self.entrythingy.bind('<Key-Return>',
self.print_contents)
def print_contents(self, event):
print("hi. contents of entry is now ---->",
self.contents.get())
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The Window Manager
^^^^^^^^^^^^^^^^^^
.. index:: single: window manager (widgets)
In Tk, there is a utility command, ``wm``, for interacting with the window
manager. Options to the ``wm`` command allow you to control things like titles,
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placement, icon bitmaps, and the like. In :mod:`tkinter`, these commands have
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been implemented as methods on the :class:`Wm` class. Toplevel widgets are
subclassed from the :class:`Wm` class, and so can call the :class:`Wm` methods
directly.
To get at the toplevel window that contains a given widget, you can often just
refer to the widget's master. Of course if the widget has been packed inside of
a frame, the master won't represent a toplevel window. To get at the toplevel
window that contains an arbitrary widget, you can call the :meth:`_root` method.
This method begins with an underscore to denote the fact that this function is
part of the implementation, and not an interface to Tk functionality.
Here are some examples of typical usage::
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from tkinter import *
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class App(Frame):
def __init__(self, master=None):
Frame.__init__(self, master)
self.pack()
# create the application
myapp = App()
#
# here are method calls to the window manager class
#
myapp.master.title("My Do-Nothing Application")
myapp.master.maxsize(1000, 400)
# start the program
myapp.mainloop()
Tk Option Data Types
^^^^^^^^^^^^^^^^^^^^
.. index:: single: Tk Option Data Types
anchor
Legal values are points of the compass: ``"n"``, ``"ne"``, ``"e"``, ``"se"``,
``"s"``, ``"sw"``, ``"w"``, ``"nw"``, and also ``"center"``.
bitmap
There are eight built-in, named bitmaps: ``'error'``, ``'gray25'``,
``'gray50'``, ``'hourglass'``, ``'info'``, ``'questhead'``, ``'question'``,
``'warning'``. To specify an X bitmap filename, give the full path to the file,
preceded with an ``@``, as in ``"@/usr/contrib/bitmap/gumby.bit"``.
boolean
You can pass integers 0 or 1 or the strings ``"yes"`` or ``"no"`` .
callback
This is any Python function that takes no arguments. For example::
def print_it():
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print("hi there")
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fred["command"] = print_it
color
Colors can be given as the names of X colors in the rgb.txt file, or as strings
representing RGB values in 4 bit: ``"#RGB"``, 8 bit: ``"#RRGGBB"``, 12 bit"
``"#RRRGGGBBB"``, or 16 bit ``"#RRRRGGGGBBBB"`` ranges, where R,G,B here
represent any legal hex digit. See page 160 of Ousterhout's book for details.
cursor
The standard X cursor names from :file:`cursorfont.h` can be used, without the
``XC_`` prefix. For example to get a hand cursor (:const:`XC_hand2`), use the
string ``"hand2"``. You can also specify a bitmap and mask file of your own.
See page 179 of Ousterhout's book.
distance
Screen distances can be specified in either pixels or absolute distances.
Pixels are given as numbers and absolute distances as strings, with the trailing
character denoting units: ``c`` for centimetres, ``i`` for inches, ``m`` for
millimetres, ``p`` for printer's points. For example, 3.5 inches is expressed
as ``"3.5i"``.
font
Tk uses a list font name format, such as ``{courier 10 bold}``. Font sizes with
positive numbers are measured in points; sizes with negative numbers are
measured in pixels.
geometry
This is a string of the form ``widthxheight``, where width and height are
measured in pixels for most widgets (in characters for widgets displaying text).
For example: ``fred["geometry"] = "200x100"``.
justify
Legal values are the strings: ``"left"``, ``"center"``, ``"right"``, and
``"fill"``.
region
This is a string with four space-delimited elements, each of which is a legal
distance (see above). For example: ``"2 3 4 5"`` and ``"3i 2i 4.5i 2i"`` and
``"3c 2c 4c 10.43c"`` are all legal regions.
relief
Determines what the border style of a widget will be. Legal values are:
``"raised"``, ``"sunken"``, ``"flat"``, ``"groove"``, and ``"ridge"``.
scrollcommand
This is almost always the :meth:`!set` method of some scrollbar widget, but can
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be any widget method that takes a single argument. Refer to the file
:file:`Demo/tkinter/matt/canvas-with-scrollbars.py` in the Python source
distribution for an example.
wrap:
Must be one of: ``"none"``, ``"char"``, or ``"word"``.
Bindings and Events
^^^^^^^^^^^^^^^^^^^
.. index::
single: bind (widgets)
single: events (widgets)
The bind method from the widget command allows you to watch for certain events
and to have a callback function trigger when that event type occurs. The form
of the bind method is::
def bind(self, sequence, func, add=''):
where:
sequence
is a string that denotes the target kind of event. (See the bind man page and
page 201 of John Ousterhout's book for details).
func
is a Python function, taking one argument, to be invoked when the event occurs.
An Event instance will be passed as the argument. (Functions deployed this way
are commonly known as *callbacks*.)
add
is optional, either ``''`` or ``'+'``. Passing an empty string denotes that
this binding is to replace any other bindings that this event is associated
with. Passing a ``'+'`` means that this function is to be added to the list
of functions bound to this event type.
For example::
def turnRed(self, event):
event.widget["activeforeground"] = "red"
self.button.bind("<Enter>", self.turnRed)
Notice how the widget field of the event is being accessed in the
:meth:`turnRed` callback. This field contains the widget that caught the X
event. The following table lists the other event fields you can access, and how
they are denoted in Tk, which can be useful when referring to the Tk man pages.
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+----+---------------------+----+---------------------+
| Tk | Tkinter Event Field | Tk | Tkinter Event Field |
+====+=====================+====+=====================+
| %f | focus | %A | char |
+----+---------------------+----+---------------------+
| %h | height | %E | send_event |
+----+---------------------+----+---------------------+
| %k | keycode | %K | keysym |
+----+---------------------+----+---------------------+
| %s | state | %N | keysym_num |
+----+---------------------+----+---------------------+
| %t | time | %T | type |
+----+---------------------+----+---------------------+
| %w | width | %W | widget |
+----+---------------------+----+---------------------+
| %x | x | %X | x_root |
+----+---------------------+----+---------------------+
| %y | y | %Y | y_root |
+----+---------------------+----+---------------------+
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The index Parameter
^^^^^^^^^^^^^^^^^^^
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A number of widgets require "index" parameters to be passed. These are used to
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point at a specific place in a Text widget, or to particular characters in an
Entry widget, or to particular menu items in a Menu widget.
Entry widget indexes (index, view index, etc.)
Entry widgets have options that refer to character positions in the text being
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displayed. You can use these :mod:`tkinter` functions to access these special
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points in text widgets:
AtEnd()
refers to the last position in the text
AtInsert()
refers to the point where the text cursor is
AtSelFirst()
indicates the beginning point of the selected text
AtSelLast()
denotes the last point of the selected text and finally
At(x[, y])
refers to the character at pixel location *x*, *y* (with *y* not used in the
case of a text entry widget, which contains a single line of text).
Text widget indexes
The index notation for Text widgets is very rich and is best described in the Tk
man pages.
Menu indexes (menu.invoke(), menu.entryconfig(), etc.)
Some options and methods for menus manipulate specific menu entries. Anytime a
menu index is needed for an option or a parameter, you may pass in:
* an integer which refers to the numeric position of the entry in the widget,
counted from the top, starting with 0;
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* the string ``"active"``, which refers to the menu position that is currently
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under the cursor;
* the string ``"last"`` which refers to the last menu item;
* An integer preceded by ``@``, as in ``@6``, where the integer is interpreted
as a y pixel coordinate in the menu's coordinate system;
* the string ``"none"``, which indicates no menu entry at all, most often used
with menu.activate() to deactivate all entries, and finally,
* a text string that is pattern matched against the label of the menu entry, as
scanned from the top of the menu to the bottom. Note that this index type is
considered after all the others, which means that matches for menu items
labelled ``last``, ``active``, or ``none`` may be interpreted as the above
literals, instead.
Images
^^^^^^
Bitmap/Pixelmap images can be created through the subclasses of
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:class:`tkinter.Image`:
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* :class:`BitmapImage` can be used for X11 bitmap data.
* :class:`PhotoImage` can be used for GIF and PPM/PGM color bitmaps.
Either type of image is created through either the ``file`` or the ``data``
option (other options are available as well).
The image object can then be used wherever an ``image`` option is supported by
some widget (e.g. labels, buttons, menus). In these cases, Tk will not keep a
reference to the image. When the last Python reference to the image object is
deleted, the image data is deleted as well, and Tk will display an empty box
wherever the image was used.