--- a/src/share/classes/com/sun/java/swing/plaf/gtk/GTKPainter.java	Mon Aug 31 22:30:04 2020 +0100
+++ b/src/share/classes/com/sun/java/swing/plaf/gtk/GTKPainter.java	Wed Jul 15 23:40:18 2020 +0530
@@ -185,6 +185,21 @@
         }
     }
 
+    //This is workaround used to draw the highlight
+    // when the MENU or MenuItem is selected on some platforms
+    //This should be properly fixed by reading color from css
+    private void paintComponentBackground(SynthContext context,
+                                          Graphics g, int x, int y,
+                                          int w, int h) {
+        GTKStyle style = (GTKStyle) context.getStyle();
+        Color highlightColor =
+                style.getGTKColor(GTKEngine.WidgetType.TEXT_AREA.ordinal(),
+                GTKLookAndFeel.synthStateToGTKStateType(SynthConstants.SELECTED).ordinal(),
+                ColorType.BACKGROUND.getID());
+        g.setColor(highlightColor);
+        g.fillRect(x, y, w, h);
+    }
+
     //
     // RADIO_BUTTON_MENU_ITEM
     //
@@ -196,6 +211,10 @@
         int gtkState = GTKLookAndFeel.synthStateToGTKState(
                 id, context.getComponentState());
         if (gtkState == SynthConstants.MOUSE_OVER) {
+            if (GTKLookAndFeel.is3()) {
+                paintComponentBackground(context, g, x, y, w, h);
+                return;
+            }
             synchronized (UNIXToolkit.GTK_LOCK) {
                 if (! ENGINE.paintCachedImage(g, x, y, w, h, id)) {
                     ShadowType shadow = (GTKLookAndFeel.is2_2() ?
@@ -535,34 +554,6 @@
         }
     }
 
-    private int getBrightness(Color c) {
-        return Math.max(c.getRed(), Math.max(c.getGreen(), c.getBlue()));
-    }
-
-    private int getMaxColorDiff(Color c1, Color c2) {
-        return Math.max(Math.abs(c1.getRed() - c2.getRed()),
-                Math.max(Math.abs(c1.getGreen() - c2.getGreen()),
-                        Math.abs(c1.getBlue() - c2.getBlue())));
-    }
-
-    private int scaleColorComponent(int color, double scaleFactor) {
-        return (int)(color + color * scaleFactor);
-    }
-    private Color deriveColor(Color originalColor, int originalBrightness,
-                              int targetBrightness) {
-        int r, g, b;
-        if (originalBrightness == 0) {
-            r = g = b = targetBrightness;
-        } else {
-            double scaleFactor = (targetBrightness - originalBrightness)
-                    / originalBrightness    ;
-            r = scaleColorComponent(originalColor.getRed(), scaleFactor);
-            g = scaleColorComponent(originalColor.getGreen(), scaleFactor);
-            b = scaleColorComponent(originalColor.getBlue(), scaleFactor);
-        }
-        return new Color(r, g, b);
-    }
-
     //
     // MENU
     //
@@ -579,56 +570,9 @@
         int gtkState = GTKLookAndFeel.synthStateToGTKState(
                 context.getRegion(), context.getComponentState());
         if (gtkState == SynthConstants.MOUSE_OVER) {
-            if (GTKLookAndFeel.is3() && context.getRegion() == Region.MENU) {
-                GTKStyle style = (GTKStyle)context.getStyle();
-                Color highlightColor = style.getGTKColor(
-                        GTKEngine.WidgetType.MENU_ITEM.ordinal(),
-                        gtkState, ColorType.BACKGROUND.getID());
-                Color backgroundColor = style.getGTKColor(
-                        GTKEngine.WidgetType.MENU_BAR.ordinal(),
-                        SynthConstants.ENABLED, ColorType.BACKGROUND.getID());
-
-                int minBrightness = 0, maxBrightness = 255;
-                int minBrightnessDifference = 100;
-                int actualBrightnessDifference =
-                        getMaxColorDiff(highlightColor, backgroundColor);
-                if (actualBrightnessDifference < minBrightnessDifference) {
-                    int highlightBrightness =
-                            getBrightness(highlightColor);
-                    int backgroundBrightness =
-                            getBrightness(backgroundColor);
-                    int originalHighlightBrightness =
-                            highlightBrightness;
-                    if (highlightBrightness >= backgroundBrightness) {
-                        if (backgroundBrightness + minBrightnessDifference <=
-                                maxBrightness) {
-                            highlightBrightness =
-                                    backgroundBrightness +
-                                            minBrightnessDifference;
-                        } else {
-                            highlightBrightness =
-                                    backgroundBrightness -
-                                            minBrightnessDifference;
-                        }
-                    } else {
-                        if (backgroundBrightness - minBrightnessDifference >=
-                                minBrightness) {
-                            highlightBrightness =
-                                    backgroundBrightness -
-                                            minBrightnessDifference;
-                        } else {
-                            highlightBrightness =
-                                    backgroundBrightness +
-                                            minBrightnessDifference;
-                        }
-                    }
-
-                    g.setColor(deriveColor(highlightColor,
-                            originalHighlightBrightness,
-                            highlightBrightness));
-                    g.fillRect(x, y, w, h);
-                    return;
-                }
+            if (GTKLookAndFeel.is3()) {
+                paintComponentBackground(context, g, x, y, w, h);
+                return;
             }
             Region id = Region.MENU_ITEM;
             synchronized (UNIXToolkit.GTK_LOCK) {

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/javax/swing/JMenu/JMenuSelectedColorTest.java	Wed Jul 15 23:40:18 2020 +0530
@@ -0,0 +1,206 @@
+/*
+ * Copyright (c) 2020, 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.
+ */
+
+/*
+ * @test
+ * @requires (os.family == "linux")
+ * @key headful
+ * @bug 8248637
+ * @summary Tests selected JMenu and JMenuitem is properly highlighted in GTKL&F
+ *  with gtk3 version
+ * @run main/othervm -Djdk.gtk.version=3 JMenuSelectedColorTest
+ */
+
+import javax.swing.JFrame;
+import javax.swing.JMenu;
+import javax.swing.JMenuBar;
+import javax.swing.JMenuItem;
+import javax.swing.JPanel;
+import javax.swing.SwingUtilities;
+import javax.swing.UIManager;
+import javax.swing.UnsupportedLookAndFeelException;
+import java.awt.BorderLayout;
+import java.awt.Color;
+import java.awt.Component;
+import java.awt.FlowLayout;
+import java.awt.Point;
+import java.awt.Rectangle;
+import java.awt.Robot;
+import java.awt.event.InputEvent;
+
+public class JMenuSelectedColorTest {
+    private static JFrame frame;
+    private static JMenu menu;
+    private static JMenuItem menuitem;
+    private static Point point;
+    private static Rectangle rect;
+    private static Robot robot;
+    private static final String GTK_LAF_CLASS = "GTKLookAndFeel";
+    private static int minColorDifference = 100;
+
+    private static void blockTillDisplayed(Component comp) {
+        Point p = null;
+        while (p == null) {
+            try {
+                p = comp.getLocationOnScreen();
+            } catch (IllegalStateException e) {
+                try {
+                    Thread.sleep(500);
+                } catch (InterruptedException ie) {
+                }
+            }
+        }
+    }
+
+    private static int getMaxColorDiff(Color c1, Color c2) {
+        return Math.max(Math.abs(c1.getRed() - c2.getRed()),
+                Math.max(Math.abs(c1.getGreen() - c2.getGreen()),
+                        Math.abs(c1.getBlue() - c2.getBlue())));
+    }
+
+    public static void main(String[] args) throws Exception {
+        if (!System.getProperty("os.name").startsWith("Linux")) {
+            System.out.println("This test is meant for Linux platform only");
+            return;
+        }
+
+        for (UIManager.LookAndFeelInfo lookAndFeelInfo :
+                UIManager.getInstalledLookAndFeels()) {
+            if (lookAndFeelInfo.getClassName().contains(GTK_LAF_CLASS)) {
+                try {
+                    UIManager.setLookAndFeel(lookAndFeelInfo.getClassName());
+                } catch (final UnsupportedLookAndFeelException ignored) {
+                    System.out.println("GTK L&F could not be set, so this " +
+                            "test can not be run in this scenario ");
+                    return;
+                }
+            }
+        }
+
+        robot = new Robot();
+        robot.setAutoDelay(100);
+
+        try {
+            SwingUtilities.invokeAndWait(new Runnable() {
+                public void run() {
+                    menu = new JMenu("         ") ;
+                    menuitem = new JMenuItem("        ");
+                    menu.add(menuitem);
+
+                    JPanel panel = new JPanel();
+                    panel.setLayout(new BorderLayout());
+
+                    JMenuBar menuBar = new JMenuBar();
+                    JPanel menuPanel = new JPanel();
+
+                    menuPanel.setLayout(new FlowLayout());
+
+                    menuBar.add(menu);
+                    menuPanel.add(menuBar);
+                    panel.add(menuPanel, BorderLayout.CENTER);
+                    frame = new JFrame("JMenuSelectedColor");
+                    frame.add(panel);
+                    frame.setSize(200, 200);
+                    frame.setAlwaysOnTop(true);
+                    frame.setLocationRelativeTo(null);
+                    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+                    frame.setVisible(true);
+                }
+            });
+
+            robot.waitForIdle();
+            robot.delay(500);
+
+            blockTillDisplayed(menu);
+            SwingUtilities.invokeAndWait(() -> {
+                point = menu.getLocationOnScreen();
+                rect = menu.getBounds();
+            });
+            robot.waitForIdle();
+            robot.delay(500);
+
+            Color backgroundColor = robot
+                    .getPixelColor(point.x+rect.width/2, point.y+rect.height/2);
+            robot.waitForIdle();
+            robot.delay(500);
+
+            menu.setSelected(true);
+            robot.waitForIdle();
+            robot.delay(500);
+
+            Color highlightColor = robot
+                    .getPixelColor(point.x+rect.width/2, point.y+rect.height/2);
+            robot.waitForIdle();
+            robot.delay(500);
+
+            int actualColorDifference = getMaxColorDiff(backgroundColor, highlightColor);
+            if (actualColorDifference < minColorDifference) {
+                throw new RuntimeException("The expected highlight color for " +
+                        "Menu was not found");
+            }
+
+            robot.mouseMove(point.x + rect.width / 2,
+                    point.y + rect.height / 2);
+            robot.waitForIdle();
+            robot.delay(500);
+
+            robot.mousePress(InputEvent.BUTTON1_DOWN_MASK);
+            robot.mouseRelease(InputEvent.BUTTON1_DOWN_MASK);
+            robot.waitForIdle();
+            robot.delay(500);
+
+            blockTillDisplayed(menuitem);
+            SwingUtilities.invokeAndWait(() -> {
+                point = menuitem.getLocationOnScreen();
+                rect = menuitem.getBounds();
+            });
+            robot.waitForIdle();
+            robot.delay(500);
+
+            backgroundColor = robot
+                    .getPixelColor(point.x+rect.width/2, point.y+rect.height/2);
+            robot.waitForIdle();
+            robot.delay(500);
+
+            robot.mouseMove(point.x + rect.width / 2,
+                    point.y + rect.height / 2);
+            robot.waitForIdle();
+            robot.delay(500);
+
+            highlightColor = robot
+                    .getPixelColor(point.x+rect.width/2, point.y+rect.height/2);
+            robot.waitForIdle();
+            robot.delay(500);
+
+            actualColorDifference = getMaxColorDiff(backgroundColor, highlightColor);
+            if (actualColorDifference < minColorDifference) {
+                throw new RuntimeException("The expected highlight color for " +
+                        "Menuitem was not found");
+            }
+        } finally {
+            if (frame != null) {
+                SwingUtilities.invokeAndWait(frame::dispose);
+            }
+        }
+    }
+}