I trashed those plist and prefs files and restarted the computer. Now, Toast launches, almost: Its icon shows up in the dock, the program asks for access to my contacts (why it needs those, I have no idea), and the menu headings show up across top of the screen. But ... no GUI in sight. If I switch to another app, or Finder, I cannot get back to Toast; it's in the Dock, it's in the Command-Tab display of open apps, but it's not accessible. And when I look at the Force Quit menu, I see that, no surprise, Toast is not responding. So, I Force-quit it and try again and ... same thing.