Fix so Auto payment occurs in Game thread

forge-core/src/main/java/forge/util/ThreadUtil.java

@@ -1,5 +1,6 @@
 package forge.util;
 
+import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
@@ -7,7 +8,6 @@ import java.util.concurrent.ThreadFactory;
 import java.util.concurrent.TimeUnit;
 
 public class ThreadUtil {
-
     static {
         System.out.printf("(ThreadUtil first call): Running on a machine with %d cpu core(s)%n", Runtime.getRuntime().availableProcessors() );
     }
@@ -25,8 +25,6 @@ public class ThreadUtil {
         }
     }
 
-    
-    
     private final static ExecutorService gameThreadPool = Executors.newCachedThreadPool(new WorkerThreadFactory("Game"));
     private static ExecutorService getGameThreadPool() { return gameThreadPool; }
     private final static ScheduledExecutorService scheduledPool = Executors.newScheduledThreadPool(2, new WorkerThreadFactory("Delayed"));
@@ -44,6 +42,28 @@ public class ThreadUtil {
     public static void invokeInGameThread(Runnable toRun) {
         getGameThreadPool().execute(toRun);
     }
+
+    public static void invokeInGameThreadAndWait(final Runnable toRun) {
+        if (isGameThread()) {
+            toRun.run(); //just run in the current thread
+            return;
+        }
+        final CountDownLatch latch = new CountDownLatch(1);
+        getGameThreadPool().execute(new Runnable() {
+            @Override
+            public void run() {
+                toRun.run();
+                latch.countDown();
+            }
+        });
+        try {
+            latch.await();
+        }
+        catch (final InterruptedException ex) {
+            throw new RuntimeException(ex);
+        }
+    }
+
     public static void delay(int milliseconds, Runnable inputUpdater) {
         getScheduledPool().schedule(inputUpdater, milliseconds, TimeUnit.MILLISECONDS);
     }

forge-gui/src/main/java/forge/gui/input/InputPayMana.java

@@ -25,6 +25,7 @@ import forge.game.spellability.AbilityManaPart;
 import forge.game.spellability.SpellAbility;
 import forge.gui.GuiChoose;
 import forge.util.Evaluator;
+import forge.util.ThreadUtil;
 import forge.view.ButtonUtil;
 
 /** 
@@ -288,13 +289,19 @@ public abstract class InputPayMana extends InputSyncronizedBase {
     protected void onOk() {
         if (supportAutoPay()) {
             //use AI utility to automatically pay mana cost if possible
-            Runnable proc = new Runnable() {
+            final Runnable proc = new Runnable() {
                 @Override
                 public void run() {
                     ComputerUtilMana.payManaCost(manaCost, saPaidFor, player);
                 }
             };
+            //must run in game thread as certain payment actions can only be automated there
+            ThreadUtil.invokeInGameThreadAndWait(new Runnable() {
+                @Override
+                public void run() {
                     runAsAi(proc);
+                }
+            });
             this.showMessage();
         }
     }