*.cancellable#parameter nullable default=null
*.*.cancellable#parameter nullable default=null

//Forward upstream
Download
  .failed#signal.error type="WebKit.DownloadError"
PrintOperation
  .failed#signal.error type="WebKit.PrintError"
WebContext
  .initialize_notification_permissions#method name="init_notification_permissions"
WebResource
  .failed#signal.error type="GLib.Error"
WebView
  .load_failed#signal.error type="GLib.Error"
  .show_option_menu#signal name="on_show_option_menu"

*.ref unowned