The XAllowDeviceEvents(3) function releases some
queued events if the client has caused a device to freeze. It has
no effect if the specified time is earlier than the
last-grab time of the most recent active grab for the client and
device, or if the specified time is later than the current X server
time.
The following describes the processing that occurs depending on
what constant you pass to the event_mode argument.
AsyncThisDevice
If the specified device is frozen by the client, event
processing for that device continues as usual. If the device is
frozen multiple times by the client on behalf of multiple separate
grabs, AsyncThisDevice thaws for all. AsyncThisDevice has no effect
if the specified device is not frozen by the client, but the device
need not be grabbed by the client.
SyncThisDevice
If the specified device is frozen and actively grabbed by the
client, event processing for that device continues normally until
the next key or button event is reported to the client. At this
time, the specified device again appears to freeze. However, if the
reported event causes the grab to be released, the specified device
does not freeze. SyncThisDevice has no effect if the
specified device is not frozen by the client or is not grabbed by
the client.
ReplayThisDevice
If the specified device is actively grabbed by the client and
is frozen as the result of an event having been sent to the client
(either from the activation of a GrabDeviceButton or from a
previous AllowDeviceEvents with mode SyncThisDevice, but not from a
GrabDevice), the grab is released and that event is completely
reprocessed. This time, however, the request ignores any passive
grabs at or above (toward the root) that the grab-window of the
grab just released. The request has no effect if the specified
device is not grabbed by the client or if it is not frozen as the
result of an event.
AsyncOtherDevices
If the remaining devices are frozen by the client, event
processing for them continues as usual. If the other devices are
frozen multiple times by the client on behalf of multiple grabs,
AsyncOtherDevices "thaws" for all. AsyncOtherDevices has no effect
if the devices are not frozen by the client.
SyncAll
If all devices are frozen by the client, event processing (for
all devices) continues normally until the next button or key event
is reported to the client for a grabbed device, at which time all
devices again appear to freeze. However, if the reported event
causes the grab to be released, then the devices do not freeze. If
any device is still grabbed, then a subsequent event for it will
still cause all devices to freeze. SyncAll has no effect unless all
devices are frozen by the client. If any device is frozen twice by
the client on behalf of two separate grabs, SyncAll thaws for both.
A subsequent freeze for SyncAll will only freeze each device
once.
AsyncAll
If all devices are frozen by the client, event processing for
all devices continues normally. If any device is frozen multiple
times by the client on behalf of multiple separate grabs, AsyncAll
thaws for all. AsyncAll has no effect unless all devices are frozen
by the client.
AsyncThisDevice, SyncThisDevice, and ReplayThisDevice have no
effect on the processing of events from the remaining devices.
AsyncOtherDevices has no effect on the processing of events from
the specified device. When the event_mode is SyncAll or
AsyncAll, the device parameter is ignored.
It is possible for several grabs of different devices by the
same or different clients to be active simultaneously. If a device
is frozen on behalf of any grab, no event processing is performed
for the device. It is possible for a single device to be frozen
because of several grabs. In this case, the freeze must be released
on behalf of each grab before events can again be processed.
XAllowDeviceEvents can generate a BadDevice or BadValue
error.
An invalid device was specified. The specified device does not
exist or has not been opened by this client through
XOpenInputDevice(). This error might also occur if the
specified device is the X keyboard or X pointer device.