diff --git a/Doc/library/idle.rst b/Doc/library/idle.rst
index c5015bf30cf..fa58e2d5942 100644
--- a/Doc/library/idle.rst
+++ b/Doc/library/idle.rst
@@ -502,8 +502,16 @@ or immediately run an existing file before editing.
Python Shell window
^^^^^^^^^^^^^^^^^^^
-The editing features described above work when entering code interactively.
-IDLE's Shell window also responds to the following keys.
+With IDLE's Shell, one enters, edits, and recalls complete statements.
+Most consoles and terminals only work with a single physical line at a time.
+
+When one pastes code into Shell, it is not compiled and possibly executed
+until one hits :kbd:`Return`. One may edit pasted code first.
+If one pastes more that one statement into Shell, the result will be a
+:exc:`SyntaxError` when multiple statements are compiled as if they were one.
+
+The editing features described in previous subsections work when entering
+code interactively. IDLE's Shell window also responds to the following keys.
* :kbd:`C-c` interrupts executing command
@@ -520,16 +528,6 @@ IDLE's Shell window also responds to the following keys.
* :kbd:`Return` while on any previous command retrieves that command
-Shell has a special facility for squeezing output lines down to a
-'Squeezed text' label. This is done automatically for output over N lines
-(N = 50 by default). N can be changed in the PyShell section of the General
-page of the Settings dialog. Output with fewer lines can be squeezed by
-right clicking on the output. This can be useful for extra long lines.
-
-Squeezed output is expanded in place by double-clicking the label.
-It can also be sent to the clipboard or a separate view window by
-right-clicking the label.
-
Text colors
^^^^^^^^^^^
@@ -666,6 +664,44 @@ If ``sys`` is reset by user code, such as with ``importlib.reload(sys)``,
IDLE's changes are lost and input from the keyboard and output to the screen
will not work correctly.
+User output in Shell
+^^^^^^^^^^^^^^^^^^^^
+
+When a program outputs text, the result is determined by the
+corresponding output device. When IDLE executes user code, ``sys.stdout``
+and ``sys.stderr`` are connected to the display area of IDLE's Shell. Some of
+its features are inherited from the underlying Tk Text widget. Others
+are programmed additions.
+
+Text widgets display a subset of Unicode, the Basic Multilingual Plane (BMP).
+Which characters get a proper glyph instead of a replacement box depends on
+the operating system and installed fonts. Newline characters cause following
+text to appear on a new line, but other control characters are replaced
+with a box. But note that the ``repr()`` function, which is used for
+interactive echo of expression values, replaces control characters
+with escape codes before they are output.
+
+Normal and error output are generally kept separate (on separate lines)
+from code input and each other. They each get different highlight colors.
+
+For SyntaxError tracebacks, the normal '^' marking where the error was
+detected is replaced by coloring the text with an error highlight.
+When code run from a file causes other exceptions, one may right click
+on a traceback line to jump to the corresponding line in an IDLE editor.
+The file will be opened if necessary.
+
+Shell has a special facility for squeezing output lines down to a
+'Squeezed text' label. This is done automatically
+for output over N lines (N = 50 by default).
+N can be changed in the PyShell section of the General
+page of the Settings dialog. Output with fewer lines can be squeezed by
+right clicking on the output. This can be useful lines long enough to slow
+down scrolling.
+
+Squeezed output is expanded in place by double-clicking the label.
+It can also be sent to the clipboard or a separate view window by
+right-clicking the label.
+
Developing tkinter applications
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/Lib/idlelib/help.html b/Lib/idlelib/help.html
index 1cd9b6913de..83bd4a1b91d 100644
--- a/Lib/idlelib/help.html
+++ b/Lib/idlelib/help.html
@@ -501,8 +501,14 @@ or immediately run an existing file before editing.
Python Shell window
-
The editing features described above work when entering code interactively.
-IDLE’s Shell window also responds to the following keys.
+
With IDLE’s Shell, one enters, edits, and recalls complete statements.
+Most consoles and terminals only work with a single physical line at a time.
+
When one pastes code into Shell, it is not compiled and possibly executed
+until one hits Return. One may edit pasted code first.
+If one pastes more that one statement into Shell, the result will be a
+SyntaxError when multiple statements are compiled as if they were one.
+
The editing features described in previous subsections work when entering
+code interactively. IDLE’s Shell window also responds to the following keys.
-
Shell has a special facility for squeezing output lines down to a
-‘Squeezed text’ label. This is done automatically for output over N lines
-(N = 50 by default). N can be changed in the PyShell section of the General
-page of the Settings dialog. Output with fewer lines can be squeezed by
-right clicking on the output. This can be useful for extra long lines.
-
Squeezed output is expanded in place by double-clicking the label.
-It can also be sent to the clipboard or a separate view window by
-right-clicking the label.
Text colors
@@ -644,6 +642,38 @@ will then be attached to that window for input and output.
IDLE’s changes are lost and input from the keyboard and output to the screen
will not work correctly.
+
+
User output in Shell
+
When a program outputs text, the result is determined by the
+corresponding output device. When IDLE executes user code, sys.stdout
+and sys.stderr are connected to the display area of IDLE’s Shell. Some of
+its features are inherited from the underlying Tk Text widget. Others
+are programmed additions.
+
Text widgets display a subset of Unicode, the Basic Multilingual Plane (BMP).
+Which characters get a proper glyph instead of a replacement box depends on
+the operating system and installed fonts. Newline characters cause following
+text to appear on a new line, but other control characters are replaced
+with a box. But note that the repr() function, which is used for
+interactive echo of expression values, replaces control characters
+with escape codes before they are output.
+
Normal and error output are generally kept separate (on separate lines)
+from code input and each other. They each get different highlight colors.
+
For SyntaxError tracebacks, the normal ‘^’ marking where the error was
+detected is replaced by coloring the text with an error highlight.
+When code run from a file causes other exceptions, one may right click
+on a traceback line to jump to the corresponding line in an IDLE editor.
+The file will be opened if necessary.
+
Shell has a special facility for squeezing output lines down to a
+‘Squeezed text’ label. This is done automatically
+for output over N lines (N = 50 by default).
+N can be changed in the PyShell section of the General
+page of the Settings dialog. Output with fewer lines can be squeezed by
+right clicking on the output. This can be useful lines long enough to slow
+down scrolling.
+
Squeezed output is expanded in place by double-clicking the label.
+It can also be sent to the clipboard or a separate view window by
+right-clicking the label.
+
Developing tkinter applications
IDLE is intentionally different from standard Python in order to
@@ -763,6 +793,7 @@ also used for testing.
Command line usage
Startup failure
Running user code
+
User output in Shell
Developing tkinter applications
Running without a subprocess
@@ -851,7 +882,7 @@ also used for testing.
- Last updated on Nov 05, 2018.
+ Last updated on Nov 06, 2018.
Found a bug?
diff --git a/Misc/NEWS.d/next/IDLE/2018-11-05-23-23-00.bpo-23220.H3SAWE.rst b/Misc/NEWS.d/next/IDLE/2018-11-05-23-23-00.bpo-23220.H3SAWE.rst
new file mode 100644
index 00000000000..77c71268ddd
--- /dev/null
+++ b/Misc/NEWS.d/next/IDLE/2018-11-05-23-23-00.bpo-23220.H3SAWE.rst
@@ -0,0 +1 @@
+Explain how IDLE's Shell displays output.