Provided by: libx11-doc_1.8.1-2_all 
NAME
XGrabKey, XUngrabKey - grab keyboard keys
SYNTAX
int XGrabKey(Display *display, int keycode, unsigned int modifiers, Window grab_window,
Bool owner_events, int pointer_mode, int keyboard_mode);
int XUngrabKey(Display *display, int keycode, unsigned int modifiers, Window grab_window);
ARGUMENTS
display Specifies the connection to the X server.
grab_window
Specifies the grab window.
keyboard_mode
Specifies further processing of keyboard events. You can pass GrabModeSync or
GrabModeAsync.
keycode Specifies the KeyCode or AnyKey.
modifiers Specifies the set of keymasks or AnyModifier. The mask is the bitwise inclusive
OR of the valid keymask bits.
owner_events
Specifies a Boolean value that indicates whether the keyboard events are to be
reported as usual.
pointer_mode
Specifies further processing of pointer events. You can pass GrabModeSync or
GrabModeAsync.
DESCRIPTION
The XGrabKey function establishes a passive grab on the keyboard. In the future, the
keyboard is actively grabbed (as for XGrabKeyboard), the last-keyboard-grab time is set to
the time at which the key was pressed (as transmitted in the KeyPress event), and the
KeyPress event is reported if all of the following conditions are true:
• The keyboard is not grabbed and the specified key (which can itself be a modifier
key) is logically pressed when the specified modifier keys are logically down, and no
other modifier keys are logically down.
• Either the grab_window is an ancestor of (or is) the focus window, or the grab_window
is a descendant of the focus window and contains the pointer.
• A passive grab on the same key combination does not exist on any ancestor of
grab_window.
The interpretation of the remaining arguments is as for XGrabKeyboard. The active grab is
terminated automatically when the logical state of the keyboard has the specified key
released (independent of the logical state of the modifier keys), at which point a
KeyRelease event is reported to the grabbing window.
Note that the logical state of a device (as seen by client applications) may lag the
physical state if device event processing is frozen.
A modifiers argument of AnyModifier is equivalent to issuing the request for all possible
modifier combinations (including the combination of no modifiers). It is not required
that all modifiers specified have currently assigned KeyCodes. A keycode argument of
AnyKey is equivalent to issuing the request for all possible KeyCodes. Otherwise, the
specified keycode must be in the range specified by min_keycode and max_keycode in the
connection setup, or a BadValue error results.
If some other client has issued a XGrabKey with the same key combination on the same
window, a BadAccess error results. When using AnyModifier or AnyKey, the request fails
completely, and a BadAccess error results (no grabs are established) if there is a
conflicting grab for any combination.
XGrabKey can generate BadAccess, BadValue, and BadWindow errors.
The XUngrabKey function releases the key combination on the specified window if it was
grabbed by this client. It has no effect on an active grab. A modifiers of AnyModifier
is equivalent to issuing the request for all possible modifier combinations (including the
combination of no modifiers). A keycode argument of AnyKey is equivalent to issuing the
request for all possible key codes.
XUngrabKey can generate BadValue and BadWindow error.
DIAGNOSTICS
BadAccess A client attempted to grab a key/button combination already grabbed by another
client.
BadValue Some numeric value falls outside the range of values accepted by the request.
Unless a specific range is specified for an argument, the full range defined by
the argument's type is accepted. Any argument defined as a set of alternatives
can generate this error.
BadWindow A value for a Window argument does not name a defined Window.
SEE ALSO
XAllowEvents(3), XGrabButton(3), XGrabKeyboard(3), XGrabPointer(3)
Xlib - C Language X Interface