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 multiple 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 XtGetSelectionValueIncremental 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 reqeuest 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, XtGetSelectionValueIncremental, and XtGetSelectionValuesIncremental will not be defered.