Fix hover state handling

We were not paying enough attention to detail when updating
hover and focus state while generating crossing events. The
invariant that we need to preserve here is that when a widget
has focus or hover, its parent does too.

gtk/gtkmain.c

@@ -1403,6 +1403,42 @@ get_virtual_notify_type (GdkNotifyType notify_type)
     }
 }
 
+/* Determine from crossing mode details whether the ultimate
+ * target is us or a descendant. Keep this code in sync with
+ * gtkeventcontrollerkey.c:update_focus
+ */
+static gboolean
+is_or_contains (gboolean      enter,
+                GdkNotifyType detail)
+{
+  gboolean is = FALSE;
+  gboolean contains = FALSE;
+
+  switch (detail)
+    {
+    case GDK_NOTIFY_VIRTUAL:
+    case GDK_NOTIFY_NONLINEAR_VIRTUAL:
+      is = FALSE;
+      contains = enter;
+      break;
+    case GDK_NOTIFY_ANCESTOR:
+    case GDK_NOTIFY_NONLINEAR:
+      is = enter;
+      contains = FALSE;
+      break;
+    case GDK_NOTIFY_INFERIOR:
+      is = enter;
+      contains = !enter;
+      break;
+    case GDK_NOTIFY_UNKNOWN:
+    default:
+      g_warning ("Unknown focus change detail");
+      return;
+    }
+
+  return is || contains;
+}
+
 static void
 synth_crossing (GtkWidget       *widget,
                 GtkWidget       *toplevel,
@@ -1451,7 +1487,7 @@ synth_crossing (GtkWidget       *widget,
   if (event->any.surface)
     g_object_ref (event->any.surface);
 
-  if (enter)
+  if (is_or_contains (enter, notify_type))
     gtk_widget_set_state_flags (widget, flags, FALSE);
   else
     gtk_widget_unset_state_flags (widget, flags);