diff --git a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatInternalFrameUI.java b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatInternalFrameUI.java
index ef7c6125..f53b3d87 100644
--- a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatInternalFrameUI.java
+++ b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatInternalFrameUI.java
@@ -206,6 +206,9 @@ public class FlatInternalFrameUI
 
 	//---- class FlatBorderListener -------------------------------------------
 
+	/**
+	 * @since 1.6
+	 */
 	protected class FlatBorderListener
 		extends BorderListener
 	{