8365379: SU3.applyInsets may produce wrong results

src/java.desktop/share/classes/com/sun/java/swing/SwingUtilities3.java

@@ -149,8 +149,8 @@ public static void applyInsets(Rectangle rect, Insets insets) {
         if (insets != null) {
             rect.x += insets.left;
             rect.y += insets.top;
-            rect.width -= (insets.right + rect.x);
-            rect.height -= (insets.bottom + rect.y);
+            rect.width -= (insets.left + insets.right);
+            rect.height -= (insets.top + insets.bottom);
         }
     }
 

src/java.desktop/share/classes/javax/swing/plaf/synth/SynthGraphicsUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -41,6 +41,7 @@
 import javax.swing.plaf.basic.BasicHTML;
 import javax.swing.text.View;
 
+import com.sun.java.swing.SwingUtilities3;
 import sun.swing.MenuItemLayoutHelper;
 import sun.swing.SwingUtilities2;
 
@@ -554,10 +555,10 @@ static Dimension getPreferredMenuItemSize(SynthContext context,
 
     static void applyInsets(Rectangle rect, Insets insets, boolean leftToRight) {
         if (insets != null) {
-            rect.x += (leftToRight ? insets.left : insets.right);
-            rect.y += insets.top;
-            rect.width -= (leftToRight ? insets.right : insets.left) + rect.x;
-            rect.height -= (insets.bottom + rect.y);
+            Insets newInsets = new Insets(insets.top, (leftToRight ? insets.left : insets.right),
+                                          insets.bottom, (leftToRight ? insets.right : insets.left));
+
+            SwingUtilities3.applyInsets(rect, newInsets);
         }
     }
 

test/jdk/javax/swing/SwingUtilities/8365379/bug8365379.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+import java.awt.Insets;
+import java.awt.Rectangle;
+
+import com.sun.java.swing.SwingUtilities3;
+
+/*
+ * @test
+ * @bug 8365379
+ * @summary Verify LineBorder edges have the same width
+ * @modules java.desktop/com.sun.java.swing
+ * @run main bug8365379
+ */
+
+public class bug8365379 {
+    public static void main(String[] args) {
+        Rectangle rect = new Rectangle(10, 20, 60, 60);
+        Insets insets = new Insets(5, 10, 15, 20);
+        Rectangle expected = new Rectangle(rect.x + insets.left,
+                                           rect.y + insets.top,
+                                           rect.width - (insets.left + insets.right),
+                                           rect.height - (insets.top + insets.bottom));
+
+        SwingUtilities3.applyInsets(rect, insets);
+        if (!rect.equals(expected)) {
+            throw new RuntimeException(("Test failed: expected " + expected + " but got " + rect));
+        }
+        System.out.println("Test passed.");
+    }
+}