G.6 Keyboard Usage on MS-Windows
This section describes the Windows-specific features related to keyboard input in Emacs.
Many key combinations (known as “keyboard shortcuts”) that have
conventional uses in MS-Windows programs conflict with traditional
Emacs key bindings. (These Emacs key bindings were established years
before Microsoft was founded.) Examples of conflicts include
C-c, C-x, C-z, and C-a.
You can redefine some of them with meanings more like the MS-Windows
meanings by enabling CUA Mode (see CUA Bindings). Another
optional feature which will make Emacs behave like other Windows
applications is Delete Selection mode (see Operating on the Region).
By default, the key labeled Alt is mapped as the Meta
key. If you wish it to produce the Alt modifier instead, set
the variable w32-alt-is-meta to a nil value.
MS-Windows reserves certain key combinations, such as
Alt-TAB and a number of Windows key combinations,
for its own use. These key combinations are intercepted by the system
before Emacs can see them. Also, on Windows 10, all Windows key
combinations are reserved by the system in such a way that they are
never propagated to applications, even if the system does not
currently define a hotkey on the specific combination. You can use
the w32-register-hot-key function to allow a key sequence to be
seen by Emacs instead of being grabbed by Windows. When registered as
a hot key, the key combination is pulled out of the system’s input
queue before it is handled by Windows, effectively overriding the
special meaning of that key sequence for Windows. The override is
only effective when Emacs is active; with other applications on the
foreground the keys behave normally.
The argument to w32-register-hot-key must be a single key with a
single modifier, in vector form that would be acceptable to
define-key. The control and shift modifiers have no effect on the
argument. The meta modifier is interpreted as the Alt key if
w32-alt-is-meta is t (the default), and the super and hyper
modifiers are interpreted according to the bindings of
w32-lwindow-modifier and w32-rwindow-modifier. Additionally, a
modifier with the trailing dash but with no key indicates that all
Windows defined hotkeys for that modifier are to be overridden in the
favor of Emacs.
For example, (w32-register-hot-key [M-tab]) lets you use
M-TAB normally in Emacs; for instance, to complete the
word or symbol at point at top level, or to complete the current
search string against previously sought strings during incremental
search. (w32-register-hot-key [s-]) with
w32-lwindow-modifier bound to super disables all the
Windows’ own Windows key based shortcuts. 26
Note that w32-register-hot-key checks the
w32-[lr]window-modifier values at the time of the function
call. Thus, you can set w32-lwindow-modifier as super,
then call (w32-register-hot-key [s-r]), and finally set
w32-rwindow-modifier as super as well. The result is
that the left Windows key together with R invokes whichever
function you have bound for the combination in Emacs, and the right
Windows key and R opens the Windows Run dialog.
The hotkey registrations always also include all the shift and
control modifier combinations for the given hotkey; that is,
registering s-a as a hotkey gives you S-s-a,
C-s-a and C-S-s-a as well.
On Windows 98 and ME, the hotkey registration is more restricted.
The desired hotkey must always be fully specified, and
w32-phantom-key-code can be customized to achieve desired
results.
The function w32-unregister-hot-key reverses the effect of
w32-register-hot-key for its argument key sequence.
By default, the CapsLock key only affects normal character
keys (it converts lower-case characters to their upper-case
variants). However, if you set the variable
w32-capslock-is-shiftlock to a non- nil value, the
CapsLock key will affect non-character keys as well, as if you
pressed the SHIFT key while typing the non-character key.
If the variable w32-enable-caps-lock is set to a nil
value, the CapsLock key produces the symbol capslock
instead of the shifted version of typed keys. The default value is
t.
Similarly, if w32-enable-num-lock is nil, the
NumLock key will produce the symbol kp-numlock. The
default is t, which causes NumLock to work as expected:
toggle the meaning of the keys on the numeric keypad.
The variable w32-apps-modifier controls the effect of the
Apps key (usually located between the right Alt and the
right Ctrl keys). Its value can be one of the symbols
hyper, super, meta, alt, control,
or shift for the respective modifier, or nil to appear
as the key apps. The default is nil.
The variable w32-lwindow-modifier determines the effect of
the left Windows key (usually labeled with start and the Windows
logo). If its value is nil (the default), the key will produce
the symbol lwindow. Setting it to one of the symbols
hyper, super, meta, alt, control,
or shift will produce the respective modifier. A similar
variable w32-rwindow-modifier controls the effect of the right
Windows key, and w32-scroll-lock-modifier does the same for the
ScrLock key. If these variables are set to nil, the
right Windows key produces the symbol rwindow and ScrLock
produces the symbol scroll. If you want ScrLock to
produce the same effect as in other applications, i.e. toggle the
Scroll Lock LED indication on the keyboard, set
w32-scroll-lock-modifier to t or any non- nil
value other than the above modifier symbols.
Emacs compiled as a native Windows application normally turns off
the Windows feature that tapping the Alt key invokes the Windows
menu. The reason is that the Alt serves as Meta in Emacs.
When using Emacs, users often press the Meta key temporarily and
then change their minds; if this has the effect of bringing up the
Windows menu, it alters the meaning of subsequent commands. Many
users find this frustrating.
You can re-enable Windows’s default handling of tapping the Alt
key by setting w32-pass-alt-to-system to a non- nil
value.
The variables w32-pass-lwindow-to-system and
w32-pass-rwindow-to-system determine whether the respective
keys are passed to Windows or swallowed by Emacs. If the value is
nil, the respective key is silently swallowed by Emacs,
otherwise it is passed to Windows. The default is t for both
of these variables. Passing each of these keys to Windows produces
its normal effect: for example, Lwindow opens the
Start menu, etc.
The variable w32-recognize-altgr controls whether the
AltGr key (if it exists on your keyboard), or its equivalent,
the combination of the right Alt and left Ctrl keys
pressed together, is recognized as the AltGr key. The default
is t, which means these keys produce AltGr; setting it
to nil causes AltGr or the equivalent key combination to
be interpreted as the combination of Ctrl and Meta
modifiers.
Some versions of MS-Windows, typically East Asian localized Windows,
enable the Input Method Manager (IMM) that allows
applications to communicate with the Input Method Editor
(IME), the native Windows input method service. Emacs uses
the IME when available to allow users to input East Asian
non-ASCII characters, similarly to Emacs’s built-in input
methods (see Input Methods). However, in some situations the
IME can get in the way if it interprets simple
ASCII keys you input as part of a key sequence that
designates a non-ASCII character. The IME can be
temporarily turned off and then on again by using the
w32-set-ime-open-status function.
Footnotes
(26)
There is one known
exception: The combination Windows-L that locks the
workstation is handled by the system on a lower level. For this
reason, w32-register-hot-key cannot override this key
combination - it always locks the computer.