https://invisible-island.net/xterm/xtoolkit/
XtCreateSelectionRequest, XtSendSelectionRequest, XtCancelSelection-
Request - bundle multiple selection conversion requests into a single
request using MULTIPLE target
#include <X11/Intrinsic.h>
void XtCreateSelectionRequest(Widget requestor, Atom selection);
void XtSendSelectionRequest(Widget requestor, Atom selection, Time
time);
void XtCancelSelectionRequest(Widget requestor, Atom selection);
requestor Specifies the widget making the request. Must be of class
Core or a subclass thereof.
selection Specifies the particular selection desired.
time Specifies the timestamp to be used in making the request.
When XtCreateSelectionRequest is called, subsequent calls to XtGetSe-
lectionValue and XtGetSelectionValueIncremental with the requestor and
selection as specified to XtCreateSelectionRequest will be bundled into
a single selection conversion request with multiple targets. The
request is actually initiated by calling XtSendSelectionRequest.
When XtSendSelectionRequest is called with a value of requestor and
selection matching a previous call to XtCreateSelectionRequest, a
selection conversion request is actually sent to the selection owner.
If a single target request is queued, that request is made. If multi-
ple targets are queued they are bundled into a single request with the
target MULTIPLE using the specified timestamp. As the conversions are
made, the callbacks associated with each XtGetSelectionValue and XtGet-
SelectionValueIncremental are invoked in turn.
Multi-threaded applications should lock the application context before
calling XtCreateSelectionRequest and release the lock after calling
XtSendSelectionRequest to ensure that the thread assembling the request
is safe from interference by another thread assembling a different
request naming the same widget and selection.
When XtCancelSelectionRequest is called, any requests queued since the
last call to XtCreateSelectionRequest are cleaned up. Subsequent calls
to XtGetSelectionValue, XtGetSelectionValues, XtGetSelectionValueIncre-
mental, and XtGetSelectionValuesIncremental will not be deferred.
X Toolkit Intrinsics – C Language Interface
Xlib - C Language X Interface
X Version 11 libXt 1.1.5.2 XtCreateSelectionRequest(3)