8218474: JComboBox display issue with GTKLookAndFeel

src/java.desktop/share/classes/com/sun/java/swing/plaf/gtk/GTKLookAndFeel.java

@@ -577,6 +577,7 @@ public Object createValue(UIDefaults table) {
                  }),
             "ComboBox.font", new FontLazyValue(Region.COMBO_BOX),
             "ComboBox.isEnterSelectablePopup", Boolean.TRUE,
+            "ComboBox.squareButton", Boolean.FALSE,
 
 
             "EditorPane.caretForeground", caretColor,

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

@@ -352,6 +352,34 @@ public void update(Graphics g, JComponent c) {
         paint(context, g);
     }
 
+    /**
+     * The minimum size is the size of the display area plus insets plus the button.
+     */
+    @Override
+    public Dimension getMinimumSize( JComponent c ) {
+        if ( !isMinimumSizeDirty ) {
+            return new Dimension(cachedMinimumSize);
+        }
+        Dimension size = getDisplaySize();
+        Insets insets = getInsets();
+        Insets arrowInsets = arrowButton.getInsets();
+        //calculate the width and height of the button
+        int buttonHeight = size.height;
+        int buttonWidth = squareButton ?
+                            buttonHeight :
+                            arrowButton.getPreferredSize().width;
+        //adjust the size based on the button width
+        size.height += insets.top + insets.bottom + arrowInsets.top
+                        + arrowInsets.bottom;
+        size.width  += insets.left + insets.right + arrowInsets.left
+                        + arrowInsets.right + buttonWidth;
+
+        cachedMinimumSize.setSize( size.width, size.height );
+        isMinimumSizeDirty = false;
+
+        return new Dimension(size);
+    }
+
     /**
      * Paints the specified component according to the Look and Feel.
      * <p>This method is not used by Synth Look and Feel.

src/java.desktop/unix/native/libawt_xawt/awt/gtk3_interface.c

@@ -1473,7 +1473,7 @@ static void gtk3_paint_arrow(WidgetType widget_type, GtkStateType state_type,
             break;
 
         case COMBO_BOX_ARROW_BUTTON:
-            s = (int)(0.3 * height + 0.5) + 1;
+            s = (int)(0.3 * MIN(height, width) + 0.5) + 1;
             a = G_PI;
             break;
 

test/jdk/javax/swing/JComboBox/TestComboBoxComponentRendering.java

@@ -0,0 +1,151 @@
+/*
+ * Copyright (c) 2022, 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
+ * @bug 8218474
+ * @key headful
+ * @requires (os.family == "linux")
+ * @summary Verifies if combobox components are rendered correctly.
+ * @run main TestComboBoxComponentRendering
+ */
+
+import java.awt.Color;
+import java.awt.Component;
+import java.awt.image.BufferedImage;
+import java.awt.Point;
+import java.awt.Rectangle;
+import java.awt.Robot;
+import java.io.File;
+import javax.imageio.ImageIO;
+import javax.swing.JComboBox;
+import javax.swing.JFrame;
+import javax.swing.JLabel;
+import javax.swing.JList;
+import javax.swing.ListCellRenderer;
+import javax.swing.SwingUtilities;
+import javax.swing.UIManager;
+import javax.swing.UnsupportedLookAndFeelException;
+
+public class TestComboBoxComponentRendering {
+    private static JFrame frame;
+    private static JComboBox cb;
+    private static Robot robot;
+
+    public static void main(String[] args) throws Exception {
+        robot = new Robot();
+        robot.setAutoDelay(100);
+
+        for (UIManager.LookAndFeelInfo laf :
+                UIManager.getInstalledLookAndFeels()) {
+            if (!laf.getClassName().contains("MotifLookAndFeel") &&
+                !laf.getClassName().contains("MetalLookAndFeel")) {
+                System.out.println("Testing LAF: " + laf.getClassName());
+                SwingUtilities.invokeAndWait(() -> setLookAndFeel(laf));
+                doTesting(laf);
+            }
+        }
+    }
+
+    private static void setLookAndFeel(UIManager.LookAndFeelInfo laf) {
+        try {
+            UIManager.setLookAndFeel(laf.getClassName());
+        } catch (UnsupportedLookAndFeelException ignored) {
+            System.out.println("Unsupported LAF: " + laf.getClassName());
+        } catch (ClassNotFoundException | InstantiationException
+                 | IllegalAccessException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    private static void doTesting(UIManager.LookAndFeelInfo laf)
+            throws Exception {
+        try {
+            SwingUtilities.invokeAndWait(() -> {
+                createAndShowUI();
+            });
+            boolean passed = false;
+            robot.waitForIdle();
+            robot.delay(1000);
+
+            Point pt = cb.getLocationOnScreen();
+            BufferedImage img = robot.createScreenCapture(
+                    new Rectangle(pt.x, pt.y, cb.getWidth(), cb.getHeight()));
+            for (int x = 20; x < img.getWidth()-20; ++x) {
+                for (int y = 20; y < img.getHeight()-20; ++y) {
+                    if (img.getRGB(x,y) == Color.RED.getRGB()) {
+                        passed = true;
+                        break;
+                    }
+                }
+                if (passed)
+                    break;
+            }
+
+            if (passed) {
+                System.out.println("Passed");
+            } else {
+                ImageIO.write(img, "png",
+                        new File("ComboBox.png"));
+                throw new RuntimeException("ComboBox components not rendered" +
+                        " correctly for: " + laf.getClassName());
+            }
+        } finally {
+            SwingUtilities.invokeAndWait(() -> {
+                if (frame != null) {
+                    frame.dispose();
+                }
+            });
+        }
+    }
+
+    private static void createAndShowUI() {
+        String[] petStrings = { "Bird", "Cat", "Dog", "Rabbit", "Pig" };
+        frame = new JFrame();
+        cb = new JComboBox(petStrings);
+        cb.setRenderer(new ComboBoxCustomRenderer());
+        frame.pack();
+        frame.add(cb);
+        frame.setSize(200,250);
+        frame.setLocationRelativeTo(null);
+        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+        frame.setVisible(true);
+    }
+}
+
+class ComboBoxCustomRenderer extends JLabel
+        implements ListCellRenderer {
+
+    public ComboBoxCustomRenderer() {
+        setOpaque(true);
+        setHorizontalAlignment(CENTER);
+        setVerticalAlignment(CENTER);
+    }
+
+    public Component getListCellRendererComponent(JList list, Object value,
+                        int index, boolean isSelected, boolean cellHasFocus) {
+        setText(value.toString());
+        setForeground(Color.RED);
+        return this;
+    }
+}

test/jdk/javax/swing/JComboBox/TestComboBoxHeight.java

@@ -24,7 +24,7 @@
 /*
  * @test
  * @key headful
- * @bug 4517214
+ * @bug 4517214 8218474
  * @summary Tests that comboBox is not doubleheight if editable and has TitledBorder
 */