diff --git a/releasenotes.txt b/releasenotes.txt
index c73d4c100..5f055014d 100644
--- a/releasenotes.txt
+++ b/releasenotes.txt
@@ -1,3 +1,7 @@
+15.2.3
+  - The new "Tooltip Indicator" feature lets you see which user interface elements provide a tooltip.
+  - A rarely occurring "ConcurrentModificationException" issue was corrected.
+
 15.2.2
   - Automatic "Where" clause adjustment in SQL console did not work correctly for queries with an "Order by" clause, but no "Where".
     This was corrected.
diff --git a/src/main/engine/net/sf/jailer/database/Session.java b/src/main/engine/net/sf/jailer/database/Session.java
index a5e13e398..667ea7e52 100644
--- a/src/main/engine/net/sf/jailer/database/Session.java
+++ b/src/main/engine/net/sf/jailer/database/Session.java
@@ -1512,10 +1512,12 @@ public class Session {
 	 * @param owner the class that owns the properties
 	 */
 	public void removeSessionProperties(Class<?> owner) {
-		Iterator<Map.Entry<String, Object>> i = sessionProperty.entrySet().iterator();
-		while (i.hasNext()) {
-			if (i.next().getKey().startsWith(owner.getName() + ".")) {
-				i.remove();
+		synchronized (sessionProperty) {
+			Iterator<Map.Entry<String, Object>> i = sessionProperty.entrySet().iterator();
+			while (i.hasNext()) {
+				if (i.next().getKey().startsWith(owner.getName() + ".")) {
+					i.remove();
+				}
 			}
 		}
 	}
diff --git a/src/main/gui/net/sf/jailer/ui/DataModelManagerDialog.java b/src/main/gui/net/sf/jailer/ui/DataModelManagerDialog.java
index c9055f313..e895dfc85 100644
--- a/src/main/gui/net/sf/jailer/ui/DataModelManagerDialog.java
+++ b/src/main/gui/net/sf/jailer/ui/DataModelManagerDialog.java
@@ -726,6 +726,8 @@ public abstract class DataModelManagerDialog extends javax.swing.JFrame {
 			public void windowActivated(WindowEvent e) {
 			}
 		});
+		
+		UIUtil.initToolTips(this);
 	}
 
 	public static void start(String module, boolean withStartupWizzard, ExecutionContext executionContext) {
diff --git a/src/main/gui/net/sf/jailer/ui/UIUtil.java b/src/main/gui/net/sf/jailer/ui/UIUtil.java
index 787fa5281..6ce296e28 100644
--- a/src/main/gui/net/sf/jailer/ui/UIUtil.java
+++ b/src/main/gui/net/sf/jailer/ui/UIUtil.java
@@ -2615,7 +2615,8 @@ public class UIUtil {
 					b = 7;
 				}
 				
-				g2d.setColor(c instanceof JLabel || c instanceof JTextField? new Color(255, 255, 0, 128) : new Color(255, 255, 0));
+				g2d.setColor(((c instanceof JLabel) && ((JLabel) c).getIcon() == null) || c instanceof JTextField?
+						new Color(255, 255, 0, 128) : new Color(255, 255, 0));
 				g2d.fillPolygon(new int[] {x, x + b, x}, new int[] {y, y, y + b}, 3);
 				g2d.setColor(new Color(200, 200, 0));
 				g2d.drawPolygon(new int[] {x, x + b, x}, new int[] {y, y, y + b}, 3);