Fix threading issues with wait callbacks

forge-gui/src/main/java/forge/util/WaitCallback.java

@@ -3,16 +3,32 @@ package forge.util;
 import forge.FThreads;
 
 public abstract class WaitCallback<T> extends Callback<T> implements Runnable {
+    public class Lock {
+    }
+
+    private final Lock lock = new Lock();
+
     private T result;
 
     @Override
     public final void run(T result0) {
         result = result0;
+        synchronized(lock) {
+            lock.notify();
+        }
     }
 
     public final T invokeAndWait() {
         FThreads.assertExecutedByEdt(false); //not supported if on UI thread
-        FThreads.invokeInEdtAndWait(this);
+        FThreads.invokeInEdtLater(this);
+        try {
+            synchronized(lock) {
+                lock.wait();
+            }
+        }
+        catch (InterruptedException e) {
+            e.printStackTrace();
+        }
         return result;
     }
 }