XGrabDevice(), XUngrabDevice() - grab/release the specified extension device
int XGrabDevice (Display *display, XDevice *device,
Window grab_window, Bool owner_events,
int event_count, XEventClass *event_list,
int this_device_mode, int other_devices_mode,
Time time)
XUngrabDevice (Display *display, XDevice *device, Time time)
The XGrabDevice(3) request actively grabs control of the device and generates DeviceFocusIn and DeviceFocusOut events. Further device events are reported only to the grabbing client. XGrabDevice(3) overrides any active device grab by this client. event_list is a pointer to a list of event classes. This list indicates which events the client wishes to receive while the grab is active. If owner_events is False , all generated device events are reported with respect to grab_window if selected. If owner_events is True and if a generated device event would normally be reported to this client, it is reported normally; otherwise, the event is reported with respect to the grab_window, and is only reported if specified in the event_list.
If the this_device_mode argument is GrabModeAsync , device event processing continues as usual. If the device is currently frozen by this client, then processing of device events is resumed. If the this_device_mode argument is GrabModeSync , the state of the device (as seen by client applications) appears to freeze, and the X server generates no further device events until the grabbing client issues a releasing XAllowDeviceEvents(3) call or until the device grab is released. Actual device changes are not lost while the device is frozen; they are simply queued in the server for later processing.
If other_devices_mode is GrabModeAsync , processing of events from other devices is unaffected by activation of the grab. If other_devices_mode is GrabModeSync, the state of all devices except the grabbed device (as seen by client applications) appears to freeze, and the X server generates no further events from those devices until the grabbing client issues a releasing XAllowDeviceEvents(3) call or until the device grab is released. Actual events are not lost while the devices are frozen; they are simply queued in the server for later processing.
If the device is actively grabbed by some other client, XGrabDevice(3) fails and returns AlreadyGrabbed. If grab_window is not viewable, it fails and returns GrabNotViewable. If the device is frozen by an active grab of another client, it fails and returns GrabFrozen. If the specified time is earlier than the last-device-grab time or later than the current X server time, it fails and returns GrabInvalidTime. Otherwise, the last-device-grab time is set to the specified time (CurrentTime is replaced by the current X server time).
If a grabbed device is closed by a client while an active grab by that client is in effect, the active grab is released. If the device is frozen only by an active grab of the requesting client, it is thawed.
XGrabDevice(3) can generate BadClass, BadDevice, BadValue, and BadWindow errors.
The XUngrabDevice(3) request releases the device and any queued events if this client has it actively grabbed from either XGrabDevice(3) or XGrabDeviceKey(3). If other devices are frozen by the grab, XUngrabDevice(3) thaws them. XUngrabDevice(3) does not release the device and any queued events if the specified time is earlier than the last-device-grab time or is later than the current X server time. It also generates DeviceFocusIn and DeviceFocusOut events. The X server automatically performs an UngrabDevice() request if the event window for an active device grab becomes not viewable.
XUngrabDevice(3) can generate a BadDevice error.
Programming with Xlib