If the clipboard contents callbacks were set with gtk.clipboard.Clipboard.setWithOwner, and the gtk.clipboard.Clipboard.setWithData or gtk.clipboard.Clipboard.clear has not subsequently called, returns the owner set by gtk.clipboard.Clipboard.setWithOwner.
the owner of the clipboard, if any; otherwise null.
If the clipboard contents callbacks were set with gtk.clipboard.Clipboard.setWithOwner, and the gtk.clipboard.Clipboard.setWithData or gtk.clipboard.Clipboard.clear has not subsequently called, returns the owner set by gtk.clipboard.Clipboard.setWithOwner.