a #GdkWindow or null to indicate that the the owner for the given should be unset.
an atom identifying a selection.
timestamp to use when setting the selection. If this is older than the timestamp given last time the owner was set for the given selection, the request will be ignored.
if true, and the new owner is different from the current owner, the current owner will be sent a SelectionClear event.
true if the selection owner was successfully changed to owner, otherwise false.
Sets the owner of the given selection.