message: Allow the creation of a clipboard without a window.
diff: @@ -26,6 +26,14 @@ impl Clipboard {
  Clipboard { state }
  }
  + /// Creates a new [`Clipboard`] that isn't associated with a window.
  + /// This clipboard will never contain a copied value.
  + pub fn unconnected() -> Clipboard {
  + Clipboard {
  + state: State::Unavailable,
  + }
  + }
  +
  /// Reads the current content of the [`Clipboard`] as text.
  pub fn read(&self) -> Option<String> {
  match &self.state {
  