diff --git a/src/com/gpl/rpg/atcontentstudio/Notification.java b/src/com/gpl/rpg/atcontentstudio/Notification.java
index 5054af7..fa25ebc 100644
--- a/src/com/gpl/rpg/atcontentstudio/Notification.java
+++ b/src/com/gpl/rpg/atcontentstudio/Notification.java
@@ -2,11 +2,12 @@ package com.gpl.rpg.atcontentstudio;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 public class Notification {
 
 	public static List<Notification> notifs = new ArrayList<Notification>();
-	private static List<NotificationListener> listeners = new ArrayList<NotificationListener>();
+	private static List<NotificationListener> listeners = new CopyOnWriteArrayList<NotificationListener>();
 	public static boolean showS = true, showI = true, showW = true, showE = true;
 	
 	static {
diff --git a/src/com/gpl/rpg/atcontentstudio/model/gamedata/Dialogue.java b/src/com/gpl/rpg/atcontentstudio/model/gamedata/Dialogue.java
index de8907a..7772327 100644
--- a/src/com/gpl/rpg/atcontentstudio/model/gamedata/Dialogue.java
+++ b/src/com/gpl/rpg/atcontentstudio/model/gamedata/Dialogue.java
@@ -349,18 +349,21 @@ public class Dialogue extends JSONElement {
 	@Override
 	public void elementChanged(GameDataElement oldOne, GameDataElement newOne) {
 		if (switch_to_npc == oldOne) {
+			oldOne.removeBacklink(this);
 			switch_to_npc = (NPC) newOne;
 			if (newOne != null) newOne.addBacklink(this);
 		} else {
 			if (replies != null) {
 				for (Reply r : replies) {
 					if (r.next_phrase == oldOne) {
+						oldOne.removeBacklink(this);
 						r.next_phrase = (Dialogue) newOne;
 						if (newOne != null) newOne.addBacklink(this);
 					}
 					if (r.requirements != null) {
 						for (Requirement req : r.requirements) {
 							if (req.required_obj == oldOne) {
+								oldOne.removeBacklink(this);
 								req.required_obj = newOne;
 								if (newOne != null) newOne.addBacklink(this);
 							}
@@ -371,6 +374,7 @@ public class Dialogue extends JSONElement {
 			if (rewards != null) {
 				for (Reward r : rewards) {
 					if (r.reward_obj == oldOne) {
+						oldOne.removeBacklink(this);
 						r.reward_obj = newOne;
 						if (newOne != null) newOne.addBacklink(this);
 					}
diff --git a/src/com/gpl/rpg/atcontentstudio/model/gamedata/Droplist.java b/src/com/gpl/rpg/atcontentstudio/model/gamedata/Droplist.java
index 4b33256..e00224a 100644
--- a/src/com/gpl/rpg/atcontentstudio/model/gamedata/Droplist.java
+++ b/src/com/gpl/rpg/atcontentstudio/model/gamedata/Droplist.java
@@ -194,6 +194,7 @@ public class Droplist extends JSONElement {
 		if (dropped_items != null) {
 			for (DroppedItem di : dropped_items) {
 				if (di.item == oldOne) {
+					oldOne.removeBacklink(this);
 					di.item = (Item) newOne;
 					if (newOne != null) newOne.addBacklink(this);
 				}
diff --git a/src/com/gpl/rpg/atcontentstudio/model/gamedata/Item.java b/src/com/gpl/rpg/atcontentstudio/model/gamedata/Item.java
index 1c76975..886b8ae 100644
--- a/src/com/gpl/rpg/atcontentstudio/model/gamedata/Item.java
+++ b/src/com/gpl/rpg/atcontentstudio/model/gamedata/Item.java
@@ -451,12 +451,14 @@ public class Item extends JSONElement {
 	@Override
 	public void elementChanged(GameDataElement oldOne, GameDataElement newOne) {
 		if (this.category == oldOne) {
+			oldOne.removeBacklink(this);
 			this.category = (ItemCategory) newOne;
 			if (newOne != null) newOne.addBacklink(this);
 		} else {
 			if (this.equip_effect != null && this.equip_effect.conditions != null) {
 				for (ConditionEffect c : this.equip_effect.conditions) {
 					if (c.condition == oldOne) {
+						oldOne.removeBacklink(this);
 						c.condition = (ActorCondition) newOne;
 						if (newOne != null) newOne.addBacklink(this);
 					}
@@ -465,6 +467,7 @@ public class Item extends JSONElement {
 			if (this.hit_effect != null && this.hit_effect.conditions_source != null) {
 				for (TimedConditionEffect c : this.hit_effect.conditions_source) {
 					if (c.condition == oldOne) {
+						oldOne.removeBacklink(this);
 						c.condition = (ActorCondition) newOne;
 						if (newOne != null) newOne.addBacklink(this);
 					}
@@ -473,6 +476,7 @@ public class Item extends JSONElement {
 			if (this.hit_effect != null && this.hit_effect.conditions_target != null) {
 				for (TimedConditionEffect c : this.hit_effect.conditions_target) {
 					if (c.condition == oldOne) {
+						oldOne.removeBacklink(this);
 						c.condition = (ActorCondition) newOne;
 						if (newOne != null) newOne.addBacklink(this);
 					}
@@ -482,6 +486,7 @@ public class Item extends JSONElement {
 			if (this.kill_effect != null && this.kill_effect.conditions_source != null) {
 				for (TimedConditionEffect c : this.kill_effect.conditions_source) {
 					if (c.condition == oldOne) {
+						oldOne.removeBacklink(this);
 						c.condition = (ActorCondition) newOne;
 						if (newOne != null) newOne.addBacklink(this);
 					}
diff --git a/src/com/gpl/rpg/atcontentstudio/model/gamedata/NPC.java b/src/com/gpl/rpg/atcontentstudio/model/gamedata/NPC.java
index bb973bb..e281ab1 100644
--- a/src/com/gpl/rpg/atcontentstudio/model/gamedata/NPC.java
+++ b/src/com/gpl/rpg/atcontentstudio/model/gamedata/NPC.java
@@ -357,16 +357,19 @@ public class NPC extends JSONElement {
 	@Override
 	public void elementChanged(GameDataElement oldOne, GameDataElement newOne) {
 		if (dialogue == oldOne) {
+			oldOne.removeBacklink(this);
 			this.dialogue = (Dialogue) newOne;
 			if (newOne != null) newOne.addBacklink(this);
 		} else {
 			if (this.droplist == oldOne) {
+				oldOne.removeBacklink(this);
 				this.droplist = (Droplist) newOne;
 				if (newOne != null) newOne.addBacklink(this);
 			} else {
 				if (this.hit_effect != null && this.hit_effect.conditions_source != null) {
 					for (TimedConditionEffect tce : this.hit_effect.conditions_source) {
 						if (tce.condition == oldOne) {
+							oldOne.removeBacklink(this);
 							tce.condition = (ActorCondition) newOne;
 							if (newOne != null) newOne.addBacklink(this);
 						}
@@ -375,6 +378,7 @@ public class NPC extends JSONElement {
 				if (this.hit_effect != null && this.hit_effect.conditions_target != null) {
 					for (TimedConditionEffect tce : this.hit_effect.conditions_target) {
 						if (tce.condition == oldOne) {
+							oldOne.removeBacklink(this);
 							tce.condition = (ActorCondition) newOne;
 							if (newOne != null) newOne.addBacklink(this);
 						}
diff --git a/src/com/gpl/rpg/atcontentstudio/model/maps/TMXMap.java b/src/com/gpl/rpg/atcontentstudio/model/maps/TMXMap.java
index bd38d86..c43e774 100644
--- a/src/com/gpl/rpg/atcontentstudio/model/maps/TMXMap.java
+++ b/src/com/gpl/rpg/atcontentstudio/model/maps/TMXMap.java
@@ -12,6 +12,7 @@ import java.util.Enumeration;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 import javax.swing.tree.TreeNode;
 
@@ -439,7 +440,7 @@ public class TMXMap extends GameDataElement {
 		this.link();
 		
 		changedOnDisk = false;
-		for (MapChangedOnDiskListener l : new ArrayList<TMXMap.MapChangedOnDiskListener>(listeners)) {
+		for (MapChangedOnDiskListener l : listeners) {
 			l.mapReloaded();
 		}
 	}
@@ -449,7 +450,7 @@ public class TMXMap extends GameDataElement {
 			dismissNextChangeNotif--;
 		} else {
 			changedOnDisk = true;
-			for (MapChangedOnDiskListener l : new ArrayList<TMXMap.MapChangedOnDiskListener>(listeners)) {
+			for (MapChangedOnDiskListener l : listeners) {
 				l.mapChanged();
 			}
 		}
@@ -460,7 +461,7 @@ public class TMXMap extends GameDataElement {
 		public void mapReloaded();
 	}
 	
-	private List<MapChangedOnDiskListener> listeners = new ArrayList<TMXMap.MapChangedOnDiskListener>();
+	private List<MapChangedOnDiskListener> listeners = new CopyOnWriteArrayList<TMXMap.MapChangedOnDiskListener>();
 	
 	public void addMapChangedOnDiskListener(MapChangedOnDiskListener l) {
 		listeners.add(l);
diff --git a/src/com/gpl/rpg/atcontentstudio/model/maps/TMXMapSet.java b/src/com/gpl/rpg/atcontentstudio/model/maps/TMXMapSet.java
index 5598faa..c9bcccd 100644
--- a/src/com/gpl/rpg/atcontentstudio/model/maps/TMXMapSet.java
+++ b/src/com/gpl/rpg/atcontentstudio/model/maps/TMXMapSet.java
@@ -108,7 +108,6 @@ public class TMXMapSet implements ProjectTreeNode {
 								for (WatchEvent<?> event : wk.pollEvents()) {
 									Path changed = (Path) event.context();
 									String name = changed.getFileName().toString();
-									System.out.println("Changed: "+name);
 									String id = name.substring(0, name.length() - 4);
 									TMXMap map = getMap(id);
 									if (map != null) {
diff --git a/src/com/gpl/rpg/atcontentstudio/model/maps/WorldmapSegment.java b/src/com/gpl/rpg/atcontentstudio/model/maps/WorldmapSegment.java
index b2f3162..fc2d7e3 100644
--- a/src/com/gpl/rpg/atcontentstudio/model/maps/WorldmapSegment.java
+++ b/src/com/gpl/rpg/atcontentstudio/model/maps/WorldmapSegment.java
@@ -103,7 +103,7 @@ public class WorldmapSegment extends GameDataElement {
 	@Override
 	public void elementChanged(GameDataElement oldOne, GameDataElement newOne) {
 		oldOne.removeBacklink(this);
-		newOne.addBacklink(this);
+		if(newOne != null) newOne.addBacklink(this);
 	}
 
 	@Override
diff --git a/src/com/gpl/rpg/atcontentstudio/ui/Editor.java b/src/com/gpl/rpg/atcontentstudio/ui/Editor.java
index 77c9df8..9811eb8 100644
--- a/src/com/gpl/rpg/atcontentstudio/ui/Editor.java
+++ b/src/com/gpl/rpg/atcontentstudio/ui/Editor.java
@@ -14,6 +14,7 @@ import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.regex.Matcher;
 
 import javax.swing.AbstractListModel;
@@ -681,7 +682,7 @@ public abstract class Editor extends JPanel implements ProjectElementListener {
 			return null;
 		}
 
-		List<ListDataListener> listeners = new ArrayList<ListDataListener>();
+		List<ListDataListener> listeners = new CopyOnWriteArrayList<ListDataListener>();
 		
 		@Override
 		public void addListDataListener(ListDataListener l) {
diff --git a/src/com/gpl/rpg/atcontentstudio/ui/JSONCreationWizard.java b/src/com/gpl/rpg/atcontentstudio/ui/JSONCreationWizard.java
index 49f430a..48b320e 100644
--- a/src/com/gpl/rpg/atcontentstudio/ui/JSONCreationWizard.java
+++ b/src/com/gpl/rpg/atcontentstudio/ui/JSONCreationWizard.java
@@ -10,6 +10,7 @@ import java.awt.event.ItemEvent;
 import java.awt.event.ItemListener;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 import javax.swing.ComboBoxModel;
 import javax.swing.DefaultListCellRenderer;
@@ -518,7 +519,7 @@ public class JSONCreationWizard extends JDialog {
 			return DataType.values()[index];
 		}
 
-		List<ListDataListener> listeners = new ArrayList<ListDataListener>();
+		List<ListDataListener> listeners = new CopyOnWriteArrayList<ListDataListener>();
 		
 		@Override
 		public void addListDataListener(ListDataListener l) {
@@ -584,7 +585,7 @@ public class JSONCreationWizard extends JDialog {
 		public void elementCreated(JSONElement created);
 	}
 	
-	private List<CreationCompletedListener> listeners = new ArrayList<JSONCreationWizard.CreationCompletedListener>();
+	private List<CreationCompletedListener> listeners = new CopyOnWriteArrayList<JSONCreationWizard.CreationCompletedListener>();
 	
 	public void addCreationListener(CreationCompletedListener l) {
 		listeners.add(l);
diff --git a/src/com/gpl/rpg/atcontentstudio/ui/JSONImportWizard.java b/src/com/gpl/rpg/atcontentstudio/ui/JSONImportWizard.java
index c270ffd..2d9c34f 100644
--- a/src/com/gpl/rpg/atcontentstudio/ui/JSONImportWizard.java
+++ b/src/com/gpl/rpg/atcontentstudio/ui/JSONImportWizard.java
@@ -15,6 +15,7 @@ import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 import javax.swing.ButtonGroup;
 import javax.swing.ComboBoxModel;
@@ -603,7 +604,7 @@ public class JSONImportWizard extends JDialog {
 			return null;
 		}
 
-		List<ListDataListener> listeners = new ArrayList<ListDataListener>();
+		List<ListDataListener> listeners = new CopyOnWriteArrayList<ListDataListener>();
 		
 		@Override
 		public void addListDataListener(ListDataListener l) {
@@ -639,7 +640,7 @@ public class JSONImportWizard extends JDialog {
 			return DataType.values()[index];
 		}
 
-		List<ListDataListener> listeners = new ArrayList<ListDataListener>();
+		List<ListDataListener> listeners = new CopyOnWriteArrayList<ListDataListener>();
 
 		@Override
 		public void addListDataListener(ListDataListener l) {
diff --git a/src/com/gpl/rpg/atcontentstudio/ui/NotificationsPane.java b/src/com/gpl/rpg/atcontentstudio/ui/NotificationsPane.java
index c7e55ce..4e30225 100644
--- a/src/com/gpl/rpg/atcontentstudio/ui/NotificationsPane.java
+++ b/src/com/gpl/rpg/atcontentstudio/ui/NotificationsPane.java
@@ -8,6 +8,7 @@ import java.util.ArrayList;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 import javax.imageio.ImageIO;
 import javax.swing.BorderFactory;
@@ -101,7 +102,7 @@ public class NotificationsPane extends JList {
 			}
 		}
 		
-		private List<ListDataListener> listeners = new ArrayList<ListDataListener>();
+		private List<ListDataListener> listeners = new CopyOnWriteArrayList<ListDataListener>();
 		@Override
 		public void addListDataListener(ListDataListener l) {
 			listeners.add(l);
diff --git a/src/com/gpl/rpg/atcontentstudio/ui/ProjectCreationWizard.java b/src/com/gpl/rpg/atcontentstudio/ui/ProjectCreationWizard.java
index f03de88..0a5ee20 100644
--- a/src/com/gpl/rpg/atcontentstudio/ui/ProjectCreationWizard.java
+++ b/src/com/gpl/rpg/atcontentstudio/ui/ProjectCreationWizard.java
@@ -11,6 +11,7 @@ import java.io.File;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 import javax.swing.ComboBoxModel;
 import javax.swing.JButton;
@@ -67,7 +68,7 @@ public class ProjectCreationWizard extends JDialog {
 				return Project.ResourceSet.values()[index];
 			}
 
-			List<ListDataListener> listeners = new ArrayList<ListDataListener>();
+			List<ListDataListener> listeners = new CopyOnWriteArrayList<ListDataListener>();
 			
 			@Override
 			public void addListDataListener(ListDataListener l) {
diff --git a/src/com/gpl/rpg/atcontentstudio/ui/ProjectsTree.java b/src/com/gpl/rpg/atcontentstudio/ui/ProjectsTree.java
index 7d5bc42..a7648ab 100644
--- a/src/com/gpl/rpg/atcontentstudio/ui/ProjectsTree.java
+++ b/src/com/gpl/rpg/atcontentstudio/ui/ProjectsTree.java
@@ -11,6 +11,7 @@ import java.awt.event.MouseAdapter;
 import java.awt.event.MouseEvent;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 import javax.swing.ImageIcon;
 import javax.swing.JLabel;
@@ -655,7 +656,7 @@ public class ProjectsTree extends JPanel {
 			return ((ProjectTreeNode)parent).getIndex((ProjectTreeNode) child);
 		}
 
-		List<TreeModelListener> listeners = new ArrayList<TreeModelListener>();
+		List<TreeModelListener> listeners = new CopyOnWriteArrayList<TreeModelListener>();
 		
 		@Override
 		public void addTreeModelListener(TreeModelListener l) {
diff --git a/src/com/gpl/rpg/atcontentstudio/ui/TMXMapCreationWizard.java b/src/com/gpl/rpg/atcontentstudio/ui/TMXMapCreationWizard.java
index 373f6ce..c170c46 100644
--- a/src/com/gpl/rpg/atcontentstudio/ui/TMXMapCreationWizard.java
+++ b/src/com/gpl/rpg/atcontentstudio/ui/TMXMapCreationWizard.java
@@ -9,6 +9,7 @@ import java.awt.event.ActionListener;
 import java.io.File;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 import javax.swing.ButtonGroup;
 import javax.swing.ComboBoxModel;
@@ -231,7 +232,7 @@ public class TMXMapCreationWizard extends JDialog {
 		public void mapCreated(TMXMap created);
 	}
 	
-	private List<CreationCompletedListener> listeners = new ArrayList<TMXMapCreationWizard.CreationCompletedListener>();
+	private List<CreationCompletedListener> listeners = new CopyOnWriteArrayList<TMXMapCreationWizard.CreationCompletedListener>();
 	
 	public void addCreationListener(CreationCompletedListener l) {
 		listeners.add(l);
@@ -257,7 +258,7 @@ public class TMXMapCreationWizard extends JDialog {
 			return proj.getMap(index);
 		}
 
-		List<ListDataListener> listeners = new ArrayList<ListDataListener>();
+		List<ListDataListener> listeners = new CopyOnWriteArrayList<ListDataListener>();
 		
 		@Override
 		public void addListDataListener(ListDataListener l) {
diff --git a/src/com/gpl/rpg/atcontentstudio/ui/WorkspaceActions.java b/src/com/gpl/rpg/atcontentstudio/ui/WorkspaceActions.java
index 482cbbf..77761b2 100644
--- a/src/com/gpl/rpg/atcontentstudio/ui/WorkspaceActions.java
+++ b/src/com/gpl/rpg/atcontentstudio/ui/WorkspaceActions.java
@@ -12,6 +12,8 @@ import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.concurrent.ConcurrentSkipListSet;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 import javax.swing.Action;
 import javax.swing.JFileChooser;
@@ -452,10 +454,8 @@ public class WorkspaceActions {
 		public void putValue(String key, Object value) {
 			PropertyChangeEvent event = new PropertyChangeEvent(this, key, values.get(key), value);
 			values.put(key,  value);
-			synchronized(listeners) {
-				for (PropertyChangeListener l : listeners) {
-					l.propertyChange(event);
-				}
+			for (PropertyChangeListener l : listeners) {
+				l.propertyChange(event);
 			}
 		}
 
@@ -463,10 +463,8 @@ public class WorkspaceActions {
 		public void setEnabled(boolean b) {
 			PropertyChangeEvent event = new PropertyChangeEvent(this, "enabled", isEnabled(), b);
 			enabled = b;
-			synchronized(listeners) {
-				for (PropertyChangeListener l : listeners) {
-					l.propertyChange(event);
-				}
+			for (PropertyChangeListener l : listeners) {
+				l.propertyChange(event);
 			}
 		}
 
@@ -475,20 +473,16 @@ public class WorkspaceActions {
 			return enabled;
 		}
 
-		private Set<PropertyChangeListener> listeners = new HashSet<PropertyChangeListener>();
+		private List<PropertyChangeListener> listeners = new CopyOnWriteArrayList<PropertyChangeListener>();
 		
 		@Override
 		public void addPropertyChangeListener(PropertyChangeListener listener) {
-			synchronized(listeners) {
-				listeners.add(listener);
-			}
+			listeners.add(listener);
 		}
 
 		@Override
 		public void removePropertyChangeListener(PropertyChangeListener listener) {
-			synchronized(listeners) {
-				listeners.remove(listener);
-			}
+			listeners.remove(listener);
 		}
 		
 	}
diff --git a/src/com/gpl/rpg/atcontentstudio/ui/WorldmapCreationWizard.java b/src/com/gpl/rpg/atcontentstudio/ui/WorldmapCreationWizard.java
index 399bf9e..c164c3a 100644
--- a/src/com/gpl/rpg/atcontentstudio/ui/WorldmapCreationWizard.java
+++ b/src/com/gpl/rpg/atcontentstudio/ui/WorldmapCreationWizard.java
@@ -7,6 +7,7 @@ import java.awt.event.ActionEvent;
 import java.awt.event.ActionListener;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 import javax.swing.JButton;
 import javax.swing.JDialog;
@@ -144,7 +145,7 @@ public class WorldmapCreationWizard extends JDialog {
 		public void segmentCreated(WorldmapSegment created);
 	}
 	
-	private List<CreationCompletedListener> listeners = new ArrayList<WorldmapCreationWizard.CreationCompletedListener>();
+	private List<CreationCompletedListener> listeners = new CopyOnWriteArrayList<WorldmapCreationWizard.CreationCompletedListener>();
 	
 	public void addCreationListener(CreationCompletedListener l) {
 		listeners.add(l);
diff --git a/src/com/gpl/rpg/atcontentstudio/ui/WorldmapLabelEditionWizard.java b/src/com/gpl/rpg/atcontentstudio/ui/WorldmapLabelEditionWizard.java
index 50bcb09..a8b2807 100644
--- a/src/com/gpl/rpg/atcontentstudio/ui/WorldmapLabelEditionWizard.java
+++ b/src/com/gpl/rpg/atcontentstudio/ui/WorldmapLabelEditionWizard.java
@@ -7,6 +7,7 @@ import java.awt.event.ActionEvent;
 import java.awt.event.ActionListener;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 import javax.swing.JButton;
 import javax.swing.JDialog;
@@ -176,7 +177,7 @@ public class WorldmapLabelEditionWizard extends JDialog {
 		public void labelCreated(WorldmapSegment.NamedArea created);
 	}
 	
-	private List<CreationCompletedListener> listeners = new ArrayList<WorldmapLabelEditionWizard.CreationCompletedListener>();
+	private List<CreationCompletedListener> listeners = new CopyOnWriteArrayList<WorldmapLabelEditionWizard.CreationCompletedListener>();
 	
 	public void addCreationListener(CreationCompletedListener l) {
 		listeners.add(l);
diff --git a/src/com/gpl/rpg/atcontentstudio/ui/gamedataeditors/DialogueEditor.java b/src/com/gpl/rpg/atcontentstudio/ui/gamedataeditors/DialogueEditor.java
index 881fcf5..3a2ef62 100644
--- a/src/com/gpl/rpg/atcontentstudio/ui/gamedataeditors/DialogueEditor.java
+++ b/src/com/gpl/rpg/atcontentstudio/ui/gamedataeditors/DialogueEditor.java
@@ -12,6 +12,7 @@ import java.awt.event.MouseAdapter;
 import java.awt.event.MouseEvent;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 import javax.swing.DefaultListCellRenderer;
 import javax.swing.ImageIcon;
@@ -752,7 +753,7 @@ public class DialogueEditor extends JSONElementEditor {
 			}
 		}
 		
-		List<ListDataListener> listeners = new ArrayList<ListDataListener>();
+		List<ListDataListener> listeners = new CopyOnWriteArrayList<ListDataListener>();
 		
 		@Override
 		public void addListDataListener(ListDataListener l) {
@@ -917,7 +918,7 @@ public class DialogueEditor extends JSONElementEditor {
 		}
 
 
-		List<ListDataListener> listeners = new ArrayList<ListDataListener>();
+		List<ListDataListener> listeners = new CopyOnWriteArrayList<ListDataListener>();
 
 		@Override
 		public void addListDataListener(ListDataListener l) {
@@ -1031,7 +1032,7 @@ public class DialogueEditor extends JSONElementEditor {
 			}
 		}
 		
-		List<ListDataListener> listeners = new ArrayList<ListDataListener>();
+		List<ListDataListener> listeners = new CopyOnWriteArrayList<ListDataListener>();
 		
 		@Override
 		public void addListDataListener(ListDataListener l) {
diff --git a/src/com/gpl/rpg/atcontentstudio/ui/gamedataeditors/DroplistEditor.java b/src/com/gpl/rpg/atcontentstudio/ui/gamedataeditors/DroplistEditor.java
index 7e560ec..cc8a7f2 100644
--- a/src/com/gpl/rpg/atcontentstudio/ui/gamedataeditors/DroplistEditor.java
+++ b/src/com/gpl/rpg/atcontentstudio/ui/gamedataeditors/DroplistEditor.java
@@ -5,6 +5,7 @@ import java.awt.event.ActionEvent;
 import java.awt.event.ActionListener;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 import javax.swing.DefaultListCellRenderer;
 import javax.swing.ImageIcon;
@@ -196,7 +197,7 @@ public class DroplistEditor extends JSONElementEditor {
 			}
 		}
 		
-		List<ListDataListener> listeners = new ArrayList<ListDataListener>();
+		List<ListDataListener> listeners = new CopyOnWriteArrayList<ListDataListener>();
 		
 		@Override
 		public void addListDataListener(ListDataListener l) {
diff --git a/src/com/gpl/rpg/atcontentstudio/ui/gamedataeditors/ItemEditor.java b/src/com/gpl/rpg/atcontentstudio/ui/gamedataeditors/ItemEditor.java
index 6f83972..5706d89 100644
--- a/src/com/gpl/rpg/atcontentstudio/ui/gamedataeditors/ItemEditor.java
+++ b/src/com/gpl/rpg/atcontentstudio/ui/gamedataeditors/ItemEditor.java
@@ -5,6 +5,7 @@ import java.awt.event.ActionEvent;
 import java.awt.event.ActionListener;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 import javax.swing.DefaultListCellRenderer;
 import javax.swing.ImageIcon;
@@ -578,7 +579,7 @@ public class ItemEditor extends JSONElementEditor {
 			}
 		}
 		
-		List<ListDataListener> listeners = new ArrayList<ListDataListener>();
+		List<ListDataListener> listeners = new CopyOnWriteArrayList<ListDataListener>();
 		
 		@Override
 		public void addListDataListener(ListDataListener l) {
@@ -640,7 +641,7 @@ public class ItemEditor extends JSONElementEditor {
 			}
 		}
 		
-		List<ListDataListener> listeners = new ArrayList<ListDataListener>();
+		List<ListDataListener> listeners = new CopyOnWriteArrayList<ListDataListener>();
 		
 		@Override
 		public void addListDataListener(ListDataListener l) {
@@ -723,7 +724,7 @@ public class ItemEditor extends JSONElementEditor {
 			}
 		}
 		
-		List<ListDataListener> listeners = new ArrayList<ListDataListener>();
+		List<ListDataListener> listeners = new CopyOnWriteArrayList<ListDataListener>();
 		
 		@Override
 		public void addListDataListener(ListDataListener l) {
diff --git a/src/com/gpl/rpg/atcontentstudio/ui/gamedataeditors/NPCEditor.java b/src/com/gpl/rpg/atcontentstudio/ui/gamedataeditors/NPCEditor.java
index 85e889d..a98c6ab 100644
--- a/src/com/gpl/rpg/atcontentstudio/ui/gamedataeditors/NPCEditor.java
+++ b/src/com/gpl/rpg/atcontentstudio/ui/gamedataeditors/NPCEditor.java
@@ -6,6 +6,7 @@ import java.awt.event.ActionEvent;
 import java.awt.event.ActionListener;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 import javax.swing.DefaultListCellRenderer;
 import javax.swing.ImageIcon;
@@ -397,7 +398,7 @@ public class NPCEditor extends JSONElementEditor {
 			}
 		}
 		
-		List<ListDataListener> listeners = new ArrayList<ListDataListener>();
+		List<ListDataListener> listeners = new CopyOnWriteArrayList<ListDataListener>();
 		
 		@Override
 		public void addListDataListener(ListDataListener l) {
@@ -459,7 +460,7 @@ public class NPCEditor extends JSONElementEditor {
 			}
 		}
 		
-		List<ListDataListener> listeners = new ArrayList<ListDataListener>();
+		List<ListDataListener> listeners = new CopyOnWriteArrayList<ListDataListener>();
 		
 		@Override
 		public void addListDataListener(ListDataListener l) {
diff --git a/src/com/gpl/rpg/atcontentstudio/ui/gamedataeditors/QuestEditor.java b/src/com/gpl/rpg/atcontentstudio/ui/gamedataeditors/QuestEditor.java
index fdce244..2af7cdc 100644
--- a/src/com/gpl/rpg/atcontentstudio/ui/gamedataeditors/QuestEditor.java
+++ b/src/com/gpl/rpg/atcontentstudio/ui/gamedataeditors/QuestEditor.java
@@ -6,6 +6,7 @@ import java.awt.event.ActionEvent;
 import java.awt.event.ActionListener;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 import javax.swing.BorderFactory;
 import javax.swing.ImageIcon;
@@ -293,7 +294,7 @@ public class QuestEditor extends JSONElementEditor {
 			if (quest.stages.isEmpty()) quest.stages = null;
 		}
 		
-		public List<TableModelListener> listeners = new ArrayList<TableModelListener>();
+		public List<TableModelListener> listeners = new CopyOnWriteArrayList<TableModelListener>();
 		
 		@Override
 		public void addTableModelListener(TableModelListener l) {
diff --git a/src/com/gpl/rpg/atcontentstudio/ui/map/TMXMapEditor.java b/src/com/gpl/rpg/atcontentstudio/ui/map/TMXMapEditor.java
index d90d97e..923934e 100644
--- a/src/com/gpl/rpg/atcontentstudio/ui/map/TMXMapEditor.java
+++ b/src/com/gpl/rpg/atcontentstudio/ui/map/TMXMapEditor.java
@@ -22,6 +22,7 @@ import java.util.ArrayList;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 import javax.swing.BorderFactory;
 import javax.swing.ComboBoxModel;
@@ -890,7 +891,7 @@ public class TMXMapEditor extends Editor implements TMXMap.MapChangedOnDiskListe
 			return index;
 		}
 		
-		List<TreeModelListener> listeners = new ArrayList<TreeModelListener>();
+		List<TreeModelListener> listeners = new CopyOnWriteArrayList<TreeModelListener>();
 
 		@Override
 		public void addTreeModelListener(TreeModelListener l) {
@@ -999,7 +1000,7 @@ public class TMXMapEditor extends Editor implements TMXMap.MapChangedOnDiskListe
 			}
 		}
 		
-		List<ListDataListener> listeners = new ArrayList<ListDataListener>();
+		List<ListDataListener> listeners = new CopyOnWriteArrayList<ListDataListener>();
 		
 		@Override
 		public void addListDataListener(ListDataListener l) {
@@ -1078,7 +1079,7 @@ public class TMXMapEditor extends Editor implements TMXMap.MapChangedOnDiskListe
 			}
 		}
 		
-		List<ListDataListener> listeners = new ArrayList<ListDataListener>();
+		List<ListDataListener> listeners = new CopyOnWriteArrayList<ListDataListener>();
 		
 		@Override
 		public void addListDataListener(ListDataListener l) {
@@ -1150,7 +1151,7 @@ public class TMXMapEditor extends Editor implements TMXMap.MapChangedOnDiskListe
 			return availableLayers.size();
 		}
 		
-		List<ListDataListener> listeners = new ArrayList<ListDataListener>();
+		List<ListDataListener> listeners = new CopyOnWriteArrayList<ListDataListener>();
 		@Override
 		public void addListDataListener(ListDataListener l) {
 			listeners.add(l);
@@ -1206,7 +1207,7 @@ public class TMXMapEditor extends Editor implements TMXMap.MapChangedOnDiskListe
 			}
 		}
 
-		List<ListDataListener> listeners = new ArrayList<ListDataListener>();
+		List<ListDataListener> listeners = new CopyOnWriteArrayList<ListDataListener>();
 		
 		@Override
 		public void addListDataListener(ListDataListener l) {
@@ -1251,7 +1252,7 @@ public class TMXMapEditor extends Editor implements TMXMap.MapChangedOnDiskListe
 			return area.spawnGroup.get(index);
 		}
 
-		List<ListDataListener> listeners = new ArrayList<ListDataListener>();
+		List<ListDataListener> listeners = new CopyOnWriteArrayList<ListDataListener>();
 		
 		@Override
 		public void addListDataListener(ListDataListener l) {
@@ -1533,7 +1534,7 @@ public class TMXMapEditor extends Editor implements TMXMap.MapChangedOnDiskListe
 			return null;
 		}
 
-		List<ListDataListener> listeners = new ArrayList<ListDataListener>();
+		List<ListDataListener> listeners = new CopyOnWriteArrayList<ListDataListener>();
 		
 		@Override
 		public void addListDataListener(ListDataListener l) {
diff --git a/src/com/gpl/rpg/atcontentstudio/ui/sprites/SpritesheetEditor.java b/src/com/gpl/rpg/atcontentstudio/ui/sprites/SpritesheetEditor.java
index de92ffa..cf3c80d 100644
--- a/src/com/gpl/rpg/atcontentstudio/ui/sprites/SpritesheetEditor.java
+++ b/src/com/gpl/rpg/atcontentstudio/ui/sprites/SpritesheetEditor.java
@@ -15,6 +15,7 @@ import java.util.Enumeration;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 import javax.swing.BorderFactory;
 import javax.swing.DefaultListCellRenderer;
@@ -259,7 +260,7 @@ public class SpritesheetEditor extends Editor {
 			
 		}
 
-		List<TableModelListener> listeners = new ArrayList<TableModelListener>();
+		List<TableModelListener> listeners = new CopyOnWriteArrayList<TableModelListener>();
 		
 		@Override
 		public void addTableModelListener(TableModelListener l) {
@@ -358,7 +359,7 @@ public class SpritesheetEditor extends Editor {
 			return null;
 		}
 
-		List<ListDataListener> listeners = new ArrayList<ListDataListener>();
+		List<ListDataListener> listeners = new CopyOnWriteArrayList<ListDataListener>();
 		
 		@Override
 		public void addListDataListener(ListDataListener l) {
diff --git a/src/com/gpl/rpg/atcontentstudio/ui/tools/ItemsTableView.java b/src/com/gpl/rpg/atcontentstudio/ui/tools/ItemsTableView.java
index 1a079d4..32b694c 100644
--- a/src/com/gpl/rpg/atcontentstudio/ui/tools/ItemsTableView.java
+++ b/src/com/gpl/rpg/atcontentstudio/ui/tools/ItemsTableView.java
@@ -2,6 +2,7 @@ package com.gpl.rpg.atcontentstudio.ui.tools;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 import javax.swing.Icon;
 import javax.swing.ImageIcon;
@@ -200,7 +201,7 @@ public class ItemsTableView extends ElementTableView {
 			//not editable.
 		}
 
-		List<TableModelListener> listeners = new ArrayList<TableModelListener>();
+		List<TableModelListener> listeners = new CopyOnWriteArrayList<TableModelListener>();
 		
 		@Override
 		public void addTableModelListener(TableModelListener l) {
diff --git a/src/com/gpl/rpg/atcontentstudio/ui/tools/NPCsTableView.java b/src/com/gpl/rpg/atcontentstudio/ui/tools/NPCsTableView.java
index 829c2bf..5f4ddf0 100644
--- a/src/com/gpl/rpg/atcontentstudio/ui/tools/NPCsTableView.java
+++ b/src/com/gpl/rpg/atcontentstudio/ui/tools/NPCsTableView.java
@@ -2,6 +2,7 @@ package com.gpl.rpg.atcontentstudio.ui.tools;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 import javax.swing.Icon;
 import javax.swing.ImageIcon;
@@ -157,7 +158,7 @@ public class NPCsTableView extends ElementTableView {
 			//not editable.
 		}
 
-		List<TableModelListener> listeners = new ArrayList<TableModelListener>();
+		List<TableModelListener> listeners = new CopyOnWriteArrayList<TableModelListener>();
 		
 		@Override
 		public void addTableModelListener(TableModelListener l) {