Use Unicode symbol as Icon

pom.xml

@@ -162,6 +162,11 @@
 			<groupId>sc.fiji</groupId>
 			<artifactId>fiji-lib</artifactId>
 		</dependency>
+		<dependency>
+		    <groupId>com.formdev</groupId>
+		    <artifactId>flatlaf</artifactId>
+		    <scope>provided</scope>
+		</dependency>
 
 		<!-- ImgLib2 dependencies -->
 		<dependency>

src/main/java/trainableSegmentation/SymbolIcon.java

@@ -0,0 +1,83 @@
+/*-
+ * #%L
+ * Fiji distribution of ImageJ for the life sciences.
+ * %%
+ * Copyright (C) 2010 - 2024 Fiji developers.
+ * %%
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ * 
+ * This program 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 for more details.
+ * 
+ * You should have received a copy of the GNU General Public
+ * License along with this program.  If not, see
+ * <http://www.gnu.org/licenses/gpl-3.0.html>.
+ * #L%
+ */
+package trainableSegmentation;
+
+import java.awt.Color;
+import java.awt.Component;
+import java.awt.Font;
+import java.awt.Graphics;
+import java.awt.Graphics2D;
+import java.awt.RenderingHints;
+
+import javax.swing.Icon;
+import javax.swing.UIManager;
+
+import com.formdev.flatlaf.FlatLaf.DisabledIconProvider;;
+
+/**
+ * Unicode symbol as Icon
+ */
+public class SymbolIcon implements Icon, DisabledIconProvider {
+	private String symbol = null;
+	private int size;
+
+	/**
+	 * 
+	 */
+	public SymbolIcon(String symbol) {
+		this(symbol, 16);
+	}
+
+	public SymbolIcon(String symbol, int size) {
+		this.symbol = symbol;
+		this.size = size;
+	}
+
+	@Override
+	public int getIconHeight() {
+		return size;
+	}
+
+	@Override
+	public int getIconWidth() {
+		return size;
+	}
+
+	@Override
+	public void paintIcon(Component c, Graphics g, int x, int y) {
+		final Font oldFont = g.getFont();
+		final float fs = size/1.1f;
+		g.setFont(oldFont.deriveFont(fs));
+		final Color color = UIManager.getColor(c.isEnabled() ? "textText" : "textInactiveText");
+		g.setColor(color);
+		if (g instanceof Graphics2D)
+			((Graphics2D) g).setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING,
+					RenderingHints.VALUE_TEXT_ANTIALIAS_LCD_HRGB);
+		g.drawString(symbol, x, y+(int)fs);
+		g.setFont(oldFont);
+	}
+
+	@Override
+	public Icon getDisabledIcon() {
+		return this;
+	}
+}

src/main/java/trainableSegmentation/Weka_Segmentation.java

@@ -221,7 +221,7 @@ public class Weka_Segmentation implements PlugIn
 	private JButton [] addExampleButton = null;
 	private JButton[] addExampleExtras = null; // consider JideSplitButton?
 	private final JPopupMenu addExampleMenu = new JPopupMenu();
-	private final JMenuItem exampleColor = new JMenuItem(new AbstractAction("🎨 Change color…") {
+	private final JMenuItem exampleColor = new JMenuItem(new AbstractAction("Change color…", new SymbolIcon("🎨")) {
 		private static final long serialVersionUID = 1L;
 		{
 			putValue(Action.SHORT_DESCRIPTION, "Change class and traces color");
@@ -239,7 +239,7 @@ public void actionPerformed(ActionEvent e) {
 			IJ.showMessage("Failed to look up class " + label + " for color change");
 		}
 	});
-	private final JMenuItem exampleRename = new JMenuItem(new AbstractAction("✎ Rename class…") {
+	private final JMenuItem exampleRename = new JMenuItem(new AbstractAction("Rename class…", new SymbolIcon("✎")) {
 		private static final long serialVersionUID = 1L;
 		{
 			putValue(Action.SHORT_DESCRIPTION, "Change class label");
@@ -259,7 +259,7 @@ public void actionPerformed(ActionEvent e) {
 			IJ.showMessage("Failed to look up class " + label + " for label change");
 		}
 	});
-	private final JMenuItem exampleRemove = new JMenuItem(new AbstractAction("✘ Remove class") {
+	private final JMenuItem exampleRemove = new JMenuItem(new AbstractAction("Remove class", new SymbolIcon("✘")) {
 		private static final long serialVersionUID = 1L;
 		{
 			putValue(Action.SHORT_DESCRIPTION, "Remove class and all associated traces");
@@ -285,7 +285,7 @@ public void actionPerformed(ActionEvent e) {
 	});
 	/** Tag for class label name in addExampleExtras' client property bag */
 	private final Object labelTag = new Object();
-	private final JButton saveExamplesButton = new JButton(new AbstractAction("💾 Save…") {
+	private final JButton saveExamplesButton = new JButton(new AbstractAction("Save…", new SymbolIcon("💾")) {
 		private static final long serialVersionUID = 1L;
 		{
 			putValue(Action.SHORT_DESCRIPTION, "Save example ROI traces");
@@ -298,7 +298,7 @@ public void actionPerformed(ActionEvent e) {
 		}
 
 	});
-	private final JButton loadExamplesButton = new JButton(new AbstractAction("📂 Load…") {
+	private final JButton loadExamplesButton = new JButton(new AbstractAction("Load…", new SymbolIcon("📂")) {
 		private static final long serialVersionUID = 1L;
 		{
 			putValue(Action.SHORT_DESCRIPTION, "Load example ROI traces");
@@ -798,13 +798,6 @@ private class CustomWindow extends StackWindow
 
 			setTitle( Weka_Segmentation.PLUGIN_NAME + " " + Weka_Segmentation.PLUGIN_VERSION );
 
-			// remove space for a menu item icon in default look and feel
-			// https://stackoverflow.com/a/64590818/673826
-			// https://github.com/JFormDesigner/FlatLaf/issues/328
-			final Insets insets = new Insets(2, -8, 2, 2);
-			exampleColor.setMargin(insets);
-			exampleRename.setMargin(insets);
-			exampleRemove.setMargin(insets);
 			addExampleMenu.add(exampleColor);
 			addExampleMenu.add(exampleRename);
 			addExampleMenu.addSeparator();