diff -r 4eb79fa3434a -r 55b2e1d3ad2b minesweeper/src/main/java/org/apidesign/demo/minesweeper/MinesModel.java
--- a/minesweeper/src/main/java/org/apidesign/demo/minesweeper/MinesModel.java	Sat Feb 08 09:25:53 2014 +0100
+++ b/minesweeper/src/main/java/org/apidesign/demo/minesweeper/MinesModel.java	Sat Feb 08 10:07:55 2014 +0100
@@ -90,6 +90,14 @@
         }
     }
     
+    @ComputedProperty static boolean fieldShowing(GameState state) {
+        return state != null;
+    }
+    
+    @Function static void showHelp(Mines model) {
+        model.setState(null);
+    }
+    
     @Function static void smallGame(Mines model) {
         model.init(5, 5, 5);
     }