Gtk.Clipboard.prototype.request_contents

function request_contents(target:Gdk.Atom, callback:Gtk.ClipboardReceivedFunc):void {
    // Gjs wrapper for gtk_clipboard_request_contents()
}

Requests the contents of clipboard as the given target. When the results of the result are later received the supplied callback will be called.

target: an atom representing the form into which the clipboard owner should convert the selection.
callback: A function to call when the results are received (or the retrieval fails). If the retrieval fails the length field of @selection_data will be negative.