Kathleen Brade authored Oct 31, 2017 and Georg Koppen committed Nov 09, 2017

Improve UX by greatly reducing the use of modal alert dialogs. In most
cases errors are now displayed using one of three techniques:
  1. Via an overlaid error panel.
  2. As a message on the progress panel (with a Reconfigure button).
  3. On a standalone error page within the setup wizard.
Move "Restart Tor" to a separate panel.
Fix a problem where showAlert() would fail to display an alert: do not
  try to use a hidden window as the parent for the alert.
Add a showOrHideElemById() utility function and use it.