Black box: the queries of the user's train worked out once a read, lights as the driver checks them

- The stations, the signals passed, the horn points, the couplings, the
  consists and the timetable progress of the user's train are kept until
  a read adds something; the views asked for them every frame, which on
  a long session with many trains took the window down. A read that adds
  nothing no longer counts as a change.
- The lights are checked against the lamps the vehicles at the ends have
  (written by the simulator from now on), as its driver checks them: Pc 1
  without the upper headlight, with the auxiliary lamps, Pc 5 with the
  rear-end signals. Only while the user drives: the autopilot's lights
  are its own.
- A train off the platform counts at both ends: its head past the stop
  point as well as its tail before the platform's end.
- A recording without the couplings keeps the timetable for any vehicle
  of the user.
- A signal passed at danger is ringed on the map only once it was.
- In the tapes window a black box opens on a click or Enter, not when
  the arrow keys go over it.
- The viewer's screenshot of a window not laid out saves nothing and
  still closes.

Eu07.BlackBox.Viewer/Screenshot.cs

@@ -16,7 +16,8 @@ internal static class Screenshot
         window.FollowTrain = follow;
         // A few frames for the layout and the first render.
         await Task.Delay(1000);
-        if (window.Content is Control content)
+        // Not laid out (a minimised window): nothing to save, and the viewer still closes.
+        if (window.Content is Control content && content.Bounds.Width >= 1 && content.Bounds.Height >= 1)
         {
             var size = new PixelSize((int)content.Bounds.Width, (int)content.Bounds.Height);
             using var bitmap = new RenderTargetBitmap(size);