GuiChoose.order is also always invoked by EDT.

Found a right wrapper class to pass Callables to EDT,

src/main/java/forge/FThreads.java

@@ -16,13 +16,6 @@ import forge.control.input.InputSynchronized;
  */
 public class FThreads {
     
-    // This could be some bad copy of SwingWorker
-    public abstract static class RunnableWithResult<T> implements Runnable {
-        protected T result = null;
-        public T getResult() { return result; }
-
-    }
-    
     static { 
         System.out.printf("(FThreads static ctor): Running on a machine with %d cpu core(s)%n", Runtime.getRuntime().availableProcessors() );
     }

src/main/java/forge/gui/GuiChoose.java

@@ -8,6 +8,9 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
 import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Future;
+import java.util.concurrent.FutureTask;
 
 import javax.swing.JDialog;
 import javax.swing.JFrame;
@@ -104,10 +107,9 @@ public class GuiChoose {
             }
         }
         
-        FThreads.RunnableWithResult<List<T>> showChoice = new FThreads.RunnableWithResult<List<T>>() {
+        Callable<List<T>> showChoice = new Callable<List<T>>() {
-            
             @Override
-            public void run() {
+            public List<T> call() {
                 ListChooser<T> c = new ListChooser<T>(message, min, max, choices);
                 final JList list = c.getJList();
                 list.addListSelectionListener(new ListSelectionListener() {
@@ -126,12 +128,18 @@ public class GuiChoose {
                 });
                 c.show();
                 GuiUtils.clearPanelSelections();
-                result = c.getSelectedValues();
+                return c.getSelectedValues();
             }
         };
 
-        FThreads.invokeInEDTAndWait(showChoice);
+        FutureTask<List<T>> future = new FutureTask<List<T>>(showChoice);
-        return showChoice.getResult();
+        FThreads.invokeInEDTAndWait(future);
+        try { 
+            return future.get();
+        } catch (Exception e) { // should be no exception here
+            e.printStackTrace();
+        }
+        return null;
     }
 
     // Nothing to choose here. Code uses this to just show a card.
@@ -153,9 +161,13 @@ public class GuiChoose {
     }
 
     
-    public static <T> List<T> order(final String title, final String top, int remainingObjects,
+    public static <T> List<T> order(final String title, final String top, final int remainingObjects,
-            final List<T> sourceChoices, List<T> destChoices, Card referenceCard, boolean sideboardingMode) {
+            final List<T> sourceChoices, final List<T> destChoices, final Card referenceCard, final boolean sideboardingMode) {
         // An input box for handling the order of choices.
+        
+        Callable<List<T>> callable = new Callable<List<T>>() {
+            @Override
+            public List<T> call() throws Exception {
                 final JFrame frame = new JFrame();
                 DualListBox<T> dual = new DualListBox<T>(remainingObjects, sourceChoices, destChoices);
                 dual.setSecondColumnLabelText(top);
@@ -187,6 +199,17 @@ public class GuiChoose {
                 GuiUtils.clearPanelSelections();
                 return objects;
             }
+        };
+
+        FutureTask<List<T>> ft = new FutureTask<List<T>>(callable);
+        FThreads.invokeInEDTAndWait(ft);
+        try {
+            return ft.get();
+        } catch (Exception e) { // we have waited enough
+            e.printStackTrace();
+        }
+        return null;
+    }
 
     // If comparer is NULL, T has to be comparable. Otherwise you'll get an exception from inside the Arrays.sort() routine
     public static <T> T sortedOneOrNone(final String message, final T[] choices, Comparator<T> comparer) {