macOS: Fixed NPE if using JMenuBar in JInternalFrame and macOS screen menu bar is enabled (issue #90)

CHANGELOG.md

@@ -19,6 +19,8 @@ FlatLaf Change Log
 - Show mnemonics always when a menu bar is active or a popup menu is visible.
 - Hide mnemonics if window is deactivated (e.g. <kbd>Alt+Tab</kbd> to another
   window). (issue #43)
+- macOS: Fixed NPE if using `JMenuBar` in `JInternalFrame` and macOS screen menu
+  bar is enabled (with `-Dapple.laf.useScreenMenuBar=true`). (issue #90)
 
 
 ## 0.33

flatlaf-core/src/main/java/com/formdev/flatlaf/FlatLaf.java

@@ -38,6 +38,7 @@ import java.util.function.Consumer;
 import java.util.function.Function;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+import javax.swing.BorderFactory;
 import javax.swing.Icon;
 import javax.swing.ImageIcon;
 import javax.swing.JComponent;
@@ -306,9 +307,13 @@ public abstract class FlatLaf
 			UIDefaultsLoader.loadDefaultsFromProperties( getClass(), addons, getAdditionalDefaults(), isDark(), defaults );
 
 		// use Aqua MenuBarUI if Mac screen menubar is enabled
-		if( SystemInfo.IS_MAC && Boolean.getBoolean( "apple.laf.useScreenMenuBar" ) )
+		if( SystemInfo.IS_MAC && Boolean.getBoolean( "apple.laf.useScreenMenuBar" ) ) {
 			defaults.put( "MenuBarUI", "com.apple.laf.AquaMenuBarUI" );
 
+			// add defaults necessary for AquaMenuBarUI
+			defaults.put( "MenuBar.backgroundPainter", BorderFactory.createEmptyBorder() );
+		}
+
 		// initialize text antialiasing
 		putAATextInfo( defaults );
 

flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatMenuBarUI.java

@@ -49,6 +49,11 @@ public class FlatMenuBarUI
 		return new FlatMenuBarUI();
 	}
 
+	/*
+	 * WARNING: This class is not used on macOS.
+	 *          Do not add any functionality here.
+	 */
+
 	@Override
 	protected void installKeyboardActions() {
 		super.installKeyboardActions();

flatlaf-testing/src/main/java/com/formdev/flatlaf/testing/FlatInternalFrameTest.java

@@ -53,6 +53,14 @@ public class FlatInternalFrameTest
 		if( iconCheckBox.isSelected() )
 			internalFrame.setFrameIcon( new FlatFileViewFloppyDriveIcon() );
 
+		if( menuBarCheckBox.isSelected() ) {
+			JMenuBar menuBar = new JMenuBar();
+			JMenu menu = new JMenu( "I'm a Menu Bar" );
+			menu.add( new JMenuItem( "Menu Item" ) );
+			menuBar.add( menu );
+			internalFrame.setJMenuBar( menuBar );
+		}
+
 		JPanel panel = new JPanel() {
 			private final Color color = new Color( (int) (Math.random() * 0xffffff) | 0x20000000, true );
 
@@ -93,6 +101,7 @@ public class FlatInternalFrameTest
 		iconifiableCheckBox = new JCheckBox();
 		maximizableCheckBox = new JCheckBox();
 		iconCheckBox = new JCheckBox();
+		menuBarCheckBox = new JCheckBox();
 		titleLabel = new JLabel();
 		titleField = new JTextField();
 		createFrameButton = new JButton();
@@ -152,6 +161,10 @@ public class FlatInternalFrameTest
 				iconCheckBox.setText("Frame icon");
 				paletteContentPane.add(iconCheckBox, "cell 0 2");
 
+				//---- menuBarCheckBox ----
+				menuBarCheckBox.setText("Menu Bar");
+				paletteContentPane.add(menuBarCheckBox, "cell 1 2");
+
 				//---- titleLabel ----
 				titleLabel.setText("Frame title:");
 				paletteContentPane.add(titleLabel, "cell 0 3");
@@ -163,7 +176,7 @@ public class FlatInternalFrameTest
 				paletteContentPane.add(createFrameButton, "cell 1 4,alignx right,growx 0");
 			}
 			desktopPane.add(palette, JLayeredPane.PALETTE_LAYER);
-			palette.setBounds(15, 25, 220, 185);
+			palette.setBounds(15, 25, 275, 185);
 		}
 		add(desktopPane, "cell 0 0,width 600,height 600");
 		// JFormDesigner - End of component initialization  //GEN-END:initComponents
@@ -180,6 +193,7 @@ public class FlatInternalFrameTest
 	private JCheckBox iconifiableCheckBox;
 	private JCheckBox maximizableCheckBox;
 	private JCheckBox iconCheckBox;
+	private JCheckBox menuBarCheckBox;
 	private JLabel titleLabel;
 	private JTextField titleField;
 	private JButton createFrameButton;

flatlaf-testing/src/main/java/com/formdev/flatlaf/testing/FlatInternalFrameTest.jfd

@@ -56,6 +56,12 @@ new FormModel {
 					}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
 						"value": "cell 0 2"
 					} )
+					add( new FormComponent( "javax.swing.JCheckBox" ) {
+						name: "menuBarCheckBox"
+						"text": "Menu Bar"
+					}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
+						"value": "cell 1 2"
+					} )
 					add( new FormComponent( "javax.swing.JLabel" ) {
 						name: "titleLabel"
 						"text": "Frame title:"
@@ -77,7 +83,7 @@ new FormModel {
 				}, new FormLayoutConstraints( null ) {
 					"x": 15
 					"y": 25
-					"width": 220
+					"width": 275
 					"height": 185
 					"layer": 100
 				} )