/*
 * MIT License
 *
 * Copyright (c) 2020 Jannis Weis
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
 * associated documentation files (the "Software"), to deal in the Software without restriction,
 * including without limitation the rights to use, copy, modify, merge, publish, distribute,
 * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all copies or
 * substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
 * NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 */
package com.github.weisj.darklaf.components;

import javax.swing.*;

import com.github.weisj.darklaf.ui.button.DarkButtonUI;

class CloseButton extends JButton {

    protected CloseButton() {
        putClientProperty(DarkButtonUI.KEY_NO_BORDERLESS_OVERWRITE, true);
        putClientProperty(DarkButtonUI.KEY_VARIANT, DarkButtonUI.VARIANT_BORDERLESS_RECTANGULAR);
        putClientProperty(DarkButtonUI.KEY_THIN, true);
        setOpaque(false);
        setRolloverEnabled(true);
        setBorderPainted(false);
        setContentAreaFilled(false);
        setIcon(UIManager.getIcon("CloseButton.closeIcon"));
        setDisabledIcon(UIManager.getIcon("CloseButton.closeDisabledIcon"));
        setRolloverIcon(UIManager.getIcon("CloseButton.closeHoverIcon"));
    }
}

@@ -1247,16 +1247,23 @@
 tonUI;%0A%0A
+public 
 class Cl
@@ -1300,16 +1300,13 @@
    p
-rotected
+ublic
  Clo
@@ -1539,32 +1539,90 @@
 EY_THIN, true);%0A
+        putClientProperty(DarkButtonUI.KEY_SQUARE, true);%0A
         setOpaqu

Make CloseButton public.