8377727: Ghost caret and focus appear in non‑editable text fields

Reviewed-by: prr, dmarkov, aivanov

Author: Alexander Zuev

src/java.desktop/share/classes/javax/swing/text/DefaultCaret.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2024, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2026, 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
@@ -25,6 +25,7 @@
 
 package javax.swing.text;
 
+import java.awt.Color;
 import java.awt.Graphics;
 import java.awt.HeadlessException;
 import java.awt.Point;
@@ -690,7 +691,25 @@ public void paint(Graphics g) {
                     // semantics of damage we can't really get around this.
                     damage(r);
                 }
-                g.setColor(component.getCaretColor());
+                if (component.isEditable()) {
+                    g.setColor(component.getCaretColor());
+                } else {
+                    Color caretColor = component.getCaretColor();
+                    if (caretColor == null) {
+                        caretColor = g.getColor();
+                    }
+                    Color bg = component.getBackground();
+                    if (bg == null) {
+                        g.setColor(caretColor);
+                    } else {
+                        int red = (caretColor.getRed() + bg.getRed()) / 2;
+                        int green = (caretColor.getGreen() + bg.getGreen()) / 2;
+                        int blue = (caretColor.getBlue() + bg.getBlue()) / 2;
+                        int alpha = 127;
+                        Color newCaretColor = new Color(red, green, blue, alpha);
+                        g.setColor(newCaretColor);
+                    }
+                }
                 int paintWidth = getCaretWidth(r.height);
                 r.x -= paintWidth  >> 1;
                 g.fillRect(r.x, r.y, paintWidth, r.height);