python-clinic / Doc / library / idle.rst


IDLE is the Python IDE built with the :mod:`tkinter` GUI toolkit.

IDLE has the following features:

  • coded in 100% pure Python, using the :mod:`tkinter` GUI toolkit
  • cross-platform: works on Windows, Unix, and Mac OS X
  • multi-window text editor with multiple undo, Python colorizing, smart indent, call tips, and many other features
  • Python shell window (a.k.a. interactive interpreter)
  • debugger (not complete, but you can set breakpoints, view and step)


IDLE has two window types, the Shell window and the Editor window. It is possible to have multiple editor windows simultaneously. IDLE's menus dynamically change based on which window is currently selected. Each menu documented below indicates which window type it is associated with. Click on the dotted line at the top of a menu to "tear it off": a separate window containing the menu is created (for Unix and Windows only).

File menu (Shell and Editor)

New window
Create a new editing window
Open an existing file
Open module...
Open an existing module (searches sys.path)
Recent Files
Open a list of recent files
Class browser
Show classes and methods in current file
Path browser
Show sys.path directories, modules, classes and methods
Save current window to the associated file (unsaved windows have a * before and after the window title)
Save As...
Save current window to new file, which becomes the associated file
Save Copy As...
Save current window to different file without changing the associated file
Print Window
Print the current window
Close current window (asks to save if unsaved)
Close all windows and quit IDLE (asks to save if unsaved)

Edit menu (Shell and Editor)

Undo last change to current window (a maximum of 1000 changes may be undone)
Redo last undone change to current window
Copy selection into system-wide clipboard; then delete the selection
Copy selection into system-wide clipboard
Insert system-wide clipboard into window
Select All
Select the entire contents of the edit buffer
Open a search dialog box with many options
Find again
Repeat last search
Find selection
Search for the string in the selection
Find in Files...
Open a search dialog box for searching files
Open a search-and-replace dialog box
Go to line
Ask for a line number and show that line
Expand word
Expand the word you have typed to match another word in the same buffer; repeat to get a different expansion
Show call tip
After an unclosed parenthesis for a function, open a small window with function parameter hints
Show surrounding parens
Highlight the surrounding parenthesis
Show Completions
Open a scroll window allowing selection keywords and attributes. See Completions below.

Format menu (Editor window only)

Indent region
Shift selected lines right by the indent width (default 4 spaces)
Dedent region
Shift selected lines left by the indent width (default 4 spaces)
Comment out region
Insert ## in front of selected lines
Uncomment region
Remove leading # or ## from selected lines
Tabify region
Turns leading stretches of spaces into tabs. (Note: We recommend using 4 space blocks to indent Python code.)
Untabify region
Turn all tabs into the correct number of spaces
Toggle tabs
Open a dialog to switch between indenting with spaces and tabs.
New Indent Width
Open a dialog to change indent width. The accepted default by the Python community is 4 spaces.
Format Paragraph
Reformat the current blank-line-separated paragraph. All lines in the paragraph will be formatted to less than 80 columns.
Strip trailing whitespace
Removes any space characters after the end of the last non-space character

Run menu (Editor window only)

Python Shell
Open or wake up the Python Shell window
Check module
Check the syntax of the module currently open in the Editor window. If the module has not been saved IDLE will prompt the user to save the code.
Run module
Restart the shell to clean the environment, then execute the currently open module. If the module has not been saved IDLE will prompt the user to save the code.

Shell menu (Shell window only)

View Last Restart
Scroll the shell window to the last Shell restart
Restart Shell
Restart the shell to clean the environment

Debug menu (Shell window only)

Go to file/line
Look around the insert point for a filename and line number, open the file, and show the line. Useful to view the source lines referenced in an exception traceback. Available in the context menu of the Shell window.
Debugger (toggle)
This feature is not complete and considered experimental. Run commands in the shell under the debugger
Stack viewer
Show the stack traceback of the last exception
Auto-open Stack Viewer
Toggle automatically opening the stack viewer on unhandled exception

Options menu (Shell and Editor)

Configure IDLE
Open a configuration dialog. Fonts, indentation, keybindings, and color themes may be altered. Startup Preferences may be set, and additional help sources can be specified.
Code Context (toggle)(Editor Window only)
Open a pane at the top of the edit window which shows the block context of the section of code which is scrolling off the top of the window.

Windows menu (Shell and Editor)

Zoom Height
Toggles the window between normal size (40x80 initial setting) and maximum height. The initial size is in the Configure IDLE dialog under the general tab.

The rest of this menu lists the names of all open windows; select one to bring it to the foreground (deiconifying it if necessary).

Help menu (Shell and Editor)

About IDLE
Version, copyright, license, credits
Display a help file for IDLE detailing the menu options, basic editing and navigation, and other tips.
Python Docs
Access local Python documentation, if installed. Or will start a web browser and open showing the latest Python documentation.

Additional help sources may be added here with the Configure IDLE dialog under the General tab.

Editor Window context menu

  • Right-click in Editor window (Control-click on OS X)
Copy selection into system-wide clipboard; then delete selection
Copy selection into system-wide clipboard
Insert system-wide clipboard into window
Set Breakpoint
Sets a breakpoint. Breakpoints are only enabled when the debugger is open.
Clear Breakpoint
Clears the breakpoint on that line.

Shell Window context menu

  • Right-click in Python Shell window (Control-click on OS X)
Copy selection into system-wide clipboard; then delete selection
Copy selection into system-wide clipboard
Insert system-wide clipboard into window
Go to file/line
Same as in Debug menu.

Editing and navigation

Standard keybindings (like :kbd:`C-c` to copy and :kbd:`C-v` to paste) may work. Keybindings are selected in the Configure IDLE dialog.

Automatic indentation

After a block-opening statement, the next line is indented by 4 spaces (in the Python Shell window by one tab). After certain keywords (break, return etc.) the next line is dedented. In leading indentation, :kbd:`Backspace` deletes up to 4 spaces if they are there. :kbd:`Tab` inserts spaces (in the Python Shell window one tab), number depends on Indent width. Currently tabs are restricted to four spaces due to Tcl/Tk limitations.

See also the indent/dedent region commands in the edit menu.


Completions are supplied for functions, classes, and attributes of classes, both built-in and user-defined. Completions are also provided for filenames.

The AutoCompleteWindow (ACW) will open after a predefined delay (default is two seconds) after a '.' or (in a string) an os.sep is typed. If after one of those characters (plus zero or more other characters) a tab is typed the ACW will open immediately if a possible continuation is found.

If there is only one possible completion for the characters entered, a :kbd:`Tab` will supply that completion without opening the ACW.

'Show Completions' will force open a completions window, by default the :kbd:`C-space` will open a completions window. In an empty string, this will contain the files in the current directory. On a blank line, it will contain the built-in and user-defined functions and classes in the current name spaces, plus any modules imported. If some characters have been entered, the ACW will attempt to be more specific.

If a string of characters is typed, the ACW selection will jump to the entry most closely matching those characters. Entering a :kbd:`tab` will cause the longest non-ambiguous match to be entered in the Editor window or Shell. Two :kbd:`tab` in a row will supply the current ACW selection, as will return or a double click. Cursor keys, Page Up/Down, mouse selection, and the scroll wheel all operate on the ACW.

"Hidden" attributes can be accessed by typing the beginning of hidden name after a '.', e.g. '_'. This allows access to modules with __all__ set, or to class-private attributes.

Completions and the 'Expand Word' facility can save a lot of typing!

Completions are currently limited to those in the namespaces. Names in an Editor window which are not via __main__ and :data:`sys.modules` will not be found. Run the module once with your imports to correct this situation. Note that IDLE itself places quite a few modules in sys.modules, so much can be found by default, e.g. the re module.

If you don't like the ACW popping up unbidden, simply make the delay longer or disable the extension. Or another option is the delay could be set to zero. Another alternative to preventing ACW popups is to disable the call tips extension.

Python Shell window

Syntax colors

The coloring is applied in a background "thread," so you may occasionally see uncolorized text. To change the color scheme, edit the [Colors] section in :file:`config.txt`.

Python syntax colors:
Shell colors:
Console output
dark green


Upon startup with the -s option, IDLE will execute the file referenced by the environment variables :envvar:`IDLESTARTUP` or :envvar:`PYTHONSTARTUP`. IDLE first checks for IDLESTARTUP; if IDLESTARTUP is present the file referenced is run. If IDLESTARTUP is not present, IDLE checks for PYTHONSTARTUP. Files referenced by these environment variables are convenient places to store functions that are used frequently from the IDLE shell, or for executing import statements to import common modules.

In addition, Tk also loads a startup file if it is present. Note that the Tk file is loaded unconditionally. This additional file is and is looked for in the user's home directory. Statements in this file will be executed in the Tk namespace, so this file is not useful for importing functions to be used from IDLE's Python shell.

Command line usage [-c command] [-d] [-e] [-s] [-t title] [arg] ...

-c command  run this command
-d          enable debugger
-e          edit mode; arguments are files to be edited
-s          run $IDLESTARTUP or $PYTHONSTARTUP first
-t title    set title of shell window

If there are arguments:

  1. If -e is used, arguments are files opened for editing and sys.argv reflects the arguments passed to IDLE itself.
  2. Otherwise, if -c is used, all arguments are placed in sys.argv[1:...], with sys.argv[0] set to '-c'.
  3. Otherwise, if neither -e nor -c is used, the first argument is a script which is executed with the remaining arguments in sys.argv[1:...] and sys.argv[0] set to the script name. If the script name is '-', no script is executed but an interactive Python session is started; the arguments are still available in sys.argv.

Additional help sources

IDLE includes a help menu entry called "Python Docs" that will open the extensive sources of help, including tutorials, available at Selected URLs can be added or removed from the help menu at any time using the Configure IDLE dialog. See the IDLE help option in the help menu of IDLE for more information.

Other preferences

The font preferences, highlighting, keys, and general preferences can be changed via the Configure IDLE menu option. Be sure to note that keys can be user defined, IDLE ships with four built in key sets. In addition a user can create a custom key set in the Configure IDLE dialog under the keys tab.


IDLE contains an extension facility. See the beginning of config-extensions.def in the idlelib directory for further information. The default extensions are currently:

  • FormatParagraph
  • AutoExpand
  • ZoomHeight
  • ScriptBinding
  • CallTips
  • ParenMatch
  • AutoComplete
  • CodeContext