All current bugs fixed

j3270/src/main/java/org/pubvm/j3270/J3270App.java

@@ -109,7 +109,7 @@ public class J3270App extends JFrame implements ConnectionListener, ScreenUpdate
         viewMenu.add(createMenuItem("Font Size -", KeyEvent.VK_MINUS, () -> adjustFontSize(-2)));
         viewMenu.add(createMenuItem("Reset Font", KeyEvent.VK_0, () -> {
             terminalPanel.setFontSize(16);
-            pack();
+            terminalPanel.guardedPack();
         }));
         menuBar.add(viewMenu);
 
@@ -200,8 +200,7 @@ public class J3270App extends JFrame implements ConnectionListener, ScreenUpdate
         setTitle("j3270 — " + config.getHost() + ":" + config.getPort());
 
         // Resize window to match model
-        terminalPanel.revalidate();
+        terminalPanel.guardedPack();
-        pack();
 
         new Thread(() -> {
             try {
@@ -233,9 +232,11 @@ public class J3270App extends JFrame implements ConnectionListener, ScreenUpdate
 
     private void adjustFontSize(int delta) {
         int current = terminalPanel.getFontSize();
-        int newSize = Math.max(8, Math.min(36, current + delta));
+        int newSize = Math.max(8, Math.min(72, current + delta));
         terminalPanel.setFontSize(newSize);
-        pack();
+        // Pack after font change — setFontSize sets the resize guard
+        // to prevent the componentResized from re-triggering autoFitFont
+        terminalPanel.guardedPack();
     }
 
     // ========== ConnectionListener ==========
@@ -249,8 +250,7 @@ public class J3270App extends JFrame implements ConnectionListener, ScreenUpdate
 
             // Auto-resize and focus on first full session
             if (newState.isFullSession() && !oldState.isFullSession()) {
-                terminalPanel.revalidate();
+                terminalPanel.guardedPack();
-                pack();
                 terminalPanel.requestFocusInWindow();
             }
         });
@@ -293,8 +293,7 @@ public class J3270App extends JFrame implements ConnectionListener, ScreenUpdate
     @Override
     public void onScreenSizeChanged(int rows, int cols) {
         SwingUtilities.invokeLater(() -> {
-            terminalPanel.revalidate();
+            terminalPanel.guardedPack();
-            pack();
         });
     }
 

j3270/src/main/java/org/pubvm/j3270/config/Settings.java

@@ -3,6 +3,7 @@ package org.pubvm.j3270.config;
 import java.util.prefs.Preferences;
 import java.awt.Color;
 import java.io.*;
+import java.io.PrintWriter;
 import java.util.logging.Logger;
 import java.util.logging.Level;
 
@@ -171,6 +172,16 @@ public class Settings {
         log.info("Configuration loaded successfully.");
     }
 
+    // ========== Block select mode ==========
+
+    public static boolean getBlockSelectMode() {
+        return prefs.getBoolean("blockSelectMode", false);
+    }
+
+    public static void setBlockSelectMode(boolean block) {
+        prefs.putBoolean("blockSelectMode", block);
+    }
+
     private static void applyConfigEntry(String section, String key, String value) {
         switch (section) {
             case "appearance":
@@ -189,6 +200,7 @@ public class Settings {
                         break;
                     case "autoConnectHost": setAutoConnectHost(value); break;
                     case "autoConnectPort": setAutoConnectPort(Integer.parseInt(value)); break;
+                    case "blockSelectMode": setBlockSelectMode(Boolean.parseBoolean(value)); break;
                     default:
                         log.warning("Unknown behavior key: " + key);
                 }
@@ -217,4 +229,82 @@ public class Settings {
                 break;
         }
     }
+
+    // ========== Export to INI ==========
+
+    /**
+     * Export the current configuration to an INI-style file.
+     * Writes all settings including appearance, behavior, colors, and keybindings.
+     */
+    public static void exportToIniFile(String path) throws IOException {
+        try (PrintWriter w = new PrintWriter(new BufferedWriter(new FileWriter(path)))) {
+            w.println("; j3270 Configuration File");
+            w.println("; Exported on " + new java.text.SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new java.util.Date()));
+            w.println("; Load with: java -jar j3270.jar -c " + new File(path).getName());
+            w.println();
+
+            // [appearance]
+            w.println("[appearance]");
+            w.println("fontFamily = " + getFontFamily());
+            w.println("fontSize = " + getFontSize());
+            w.println();
+
+            // [behavior]
+            w.println("[behavior]");
+            w.println("startupBehavior = " + getStartupBehavior().name());
+            String acHost = getAutoConnectHost();
+            if (acHost != null && !acHost.isEmpty()) {
+                w.println("autoConnectHost = " + acHost);
+                w.println("autoConnectPort = " + getAutoConnectPort());
+            }
+            w.println("blockSelectMode = " + getBlockSelectMode());
+            w.println();
+
+            // [colors]
+            w.println("[colors]");
+            // Host colors 0-15
+            for (int i = 0; i < 16; i++) {
+                String hex = prefs.get("color_" + i, null);
+                if (hex != null) {
+                    w.println("color_" + i + " = " + hex);
+                }
+            }
+            // Mono colors
+            String[] monoKeys = {"NORMAL", "INTENSIFY", "PROTECTED", "PROTECTED_HIGH", "BACKGROUND"};
+            for (String mk : monoKeys) {
+                String hex = prefs.get("mono_" + mk, null);
+                if (hex != null) {
+                    w.println("mono_" + mk + " = " + hex);
+                }
+            }
+            w.println();
+
+            // [keybindings]
+            w.println("[keybindings]");
+            // Navigation keys
+            String[] navActions = {"ENTER", "TAB", "shift TAB", "UP", "DOWN", "LEFT", "RIGHT",
+                "HOME", "END", "PAGE_UP", "PAGE_DOWN", "ESCAPE", "INSERT", "DELETE", "BACK_SPACE", "CLEAR"};
+            for (String act : navActions) {
+                String val = prefs.get("key_" + act, null);
+                if (val != null) {
+                    w.println(act + " = " + val);
+                }
+            }
+            // PF keys
+            for (int i = 1; i <= 24; i++) {
+                String val = prefs.get("key_PF" + i, null);
+                if (val != null) {
+                    w.println("PF" + i + " = " + val);
+                }
+            }
+            // PA keys
+            for (int i = 1; i <= 3; i++) {
+                String val = prefs.get("key_PA" + i, null);
+                if (val != null) {
+                    w.println("PA" + i + " = " + val);
+                }
+            }
+        }
+        log.info("Configuration exported to: " + path);
+    }
 }

j3270/src/main/java/org/pubvm/j3270/ui/SettingsDialog.java

@@ -10,12 +10,24 @@ import java.awt.event.*;
 import java.util.HashMap;
 import java.util.Map;
 import javax.swing.table.DefaultTableModel;
+import javax.swing.table.DefaultTableCellRenderer;
+import javax.swing.table.JTableHeader;
 import javax.swing.border.LineBorder;
+import javax.swing.border.TitledBorder;
 
 public class SettingsDialog extends JDialog {
 
     private final J3270App parentApp;
 
+    // Dark theme colors
+    private static final Color DARK_BG = new Color(43, 43, 43);
+    private static final Color DARK_BG_LIGHTER = new Color(55, 55, 55);
+    private static final Color DARK_FG = new Color(224, 224, 224);
+    private static final Color DARK_BORDER = new Color(70, 70, 70);
+    private static final Color DARK_SELECTION = new Color(75, 110, 175);
+    private static final Color DARK_BUTTON_BG = new Color(60, 63, 65);
+    private static final Color DARK_FIELD_BG = new Color(50, 50, 50);
+
     // Appearance tab
     private JComboBox<String> fontBox;
     private JSpinner fontSizeSpinner;
@@ -25,6 +37,7 @@ public class SettingsDialog extends JDialog {
     private JPanel autoConnectPanel;
     private JTextField hostField;
     private JTextField portField;
+    private JCheckBox blockSelectCheck;
 
     // Advanced tab state tracking
     private final Color[] tempHostColors = new Color[16];
@@ -49,10 +62,15 @@ public class SettingsDialog extends JDialog {
         tabbedPane.addTab("Advanced", createAdvancedPanel());
 
         JPanel buttonPanel = new JPanel(new FlowLayout(FlowLayout.RIGHT));
+        JButton btnExport = new JButton("Export Config...");
         JButton btnOk = new JButton("OK");
         JButton btnApply = new JButton("Apply");
         JButton btnCancel = new JButton("Cancel");
 
+        btnExport.addActionListener((ActionEvent e) -> {
+            exportConfig();
+        });
+
         btnOk.addActionListener((ActionEvent e) -> {
             boolean success = applySettings();
             if (success) {
@@ -68,14 +86,145 @@ public class SettingsDialog extends JDialog {
             dispose();
         });
 
+        buttonPanel.add(btnExport);
+        buttonPanel.add(Box.createHorizontalStrut(20));
         buttonPanel.add(btnApply);
         buttonPanel.add(btnCancel);
         buttonPanel.add(btnOk);
 
         getContentPane().add(tabbedPane, BorderLayout.CENTER);
         getContentPane().add(buttonPanel, BorderLayout.SOUTH);
+
+        // Apply dark theme to all components for cross-platform readability
+        applyDarkTheme(getContentPane());
+        applyDarkTheme(tabbedPane);
+        applyDarkTheme(buttonPanel);
+        getContentPane().setBackground(DARK_BG);
     }
 
+    // ========== Dark Theme Utility ==========
+
+    /**
+     * Recursively apply dark theme to a component and all its children.
+     * Ensures the Settings dialog is readable on Windows, Linux, and macOS.
+     */
+    private void applyDarkTheme(Component comp) {
+        if (comp instanceof JTabbedPane) {
+            JTabbedPane tp = (JTabbedPane) comp;
+            tp.setBackground(DARK_BG);
+            tp.setForeground(DARK_FG);
+            for (int i = 0; i < tp.getTabCount(); i++) {
+                applyDarkTheme(tp.getComponentAt(i));
+            }
+            return;
+        }
+
+        if (comp instanceof JTable) {
+            JTable table = (JTable) comp;
+            table.setBackground(DARK_FIELD_BG);
+            table.setForeground(DARK_FG);
+            table.setSelectionBackground(DARK_SELECTION);
+            table.setSelectionForeground(Color.WHITE);
+            table.setGridColor(DARK_BORDER);
+            JTableHeader header = table.getTableHeader();
+            if (header != null) {
+                header.setBackground(DARK_BG_LIGHTER);
+                header.setForeground(DARK_FG);
+                DefaultTableCellRenderer headerRenderer = new DefaultTableCellRenderer();
+                headerRenderer.setBackground(DARK_BG_LIGHTER);
+                headerRenderer.setForeground(DARK_FG);
+                header.setDefaultRenderer(headerRenderer);
+            }
+            return;
+        }
+
+        if (comp instanceof JScrollPane) {
+            JScrollPane sp = (JScrollPane) comp;
+            sp.setBackground(DARK_BG);
+            sp.getViewport().setBackground(DARK_FIELD_BG);
+            applyDarkTheme(sp.getViewport().getView());
+            return;
+        }
+
+        if (comp instanceof JButton) {
+            JButton btn = (JButton) comp;
+            btn.setBackground(DARK_BUTTON_BG);
+            btn.setForeground(DARK_FG);
+            btn.setFocusPainted(false);
+            btn.setBorder(BorderFactory.createCompoundBorder(
+                new LineBorder(DARK_BORDER, 1),
+                BorderFactory.createEmptyBorder(3, 10, 3, 10)));
+            btn.setOpaque(true);
+            return;
+        }
+
+        if (comp instanceof JComboBox) {
+            JComboBox<?> cb = (JComboBox<?>) comp;
+            cb.setBackground(DARK_FIELD_BG);
+            cb.setForeground(DARK_FG);
+            return;
+        }
+
+        if (comp instanceof JSpinner) {
+            JSpinner sp = (JSpinner) comp;
+            sp.setBackground(DARK_FIELD_BG);
+            sp.setForeground(DARK_FG);
+            JComponent editor = sp.getEditor();
+            if (editor instanceof JSpinner.DefaultEditor) {
+                JTextField tf = ((JSpinner.DefaultEditor) editor).getTextField();
+                tf.setBackground(DARK_FIELD_BG);
+                tf.setForeground(DARK_FG);
+                tf.setCaretColor(DARK_FG);
+            }
+            return;
+        }
+
+        if (comp instanceof JTextField) {
+            JTextField tf = (JTextField) comp;
+            tf.setBackground(DARK_FIELD_BG);
+            tf.setForeground(DARK_FG);
+            tf.setCaretColor(DARK_FG);
+            return;
+        }
+
+        if (comp instanceof JCheckBox) {
+            JCheckBox cb = (JCheckBox) comp;
+            cb.setBackground(DARK_BG);
+            cb.setForeground(DARK_FG);
+            return;
+        }
+
+        if (comp instanceof JLabel) {
+            comp.setForeground(DARK_FG);
+            return;
+        }
+
+        // Generic panel / container
+        // Skip color swatch panels — their background IS the color
+        if (comp instanceof JPanel && "colorSwatch".equals(comp.getName())) {
+            return;
+        }
+        comp.setBackground(DARK_BG);
+        comp.setForeground(DARK_FG);
+
+        if (comp instanceof JPanel) {
+            JPanel panel = (JPanel) comp;
+            // Style titled borders
+            if (panel.getBorder() instanceof TitledBorder) {
+                TitledBorder tb = (TitledBorder) panel.getBorder();
+                tb.setTitleColor(DARK_FG);
+            }
+        }
+
+        if (comp instanceof Container) {
+            for (Component child : ((Container) comp).getComponents()) {
+                applyDarkTheme(child);
+            }
+        }
+    }
+
+    // ========== Tab Panels ==========
+
     private JPanel createAppearancePanel() {
         JPanel panel = new JPanel(new GridBagLayout());
         GridBagConstraints gbc = new GridBagConstraints();
@@ -174,8 +323,14 @@ public class SettingsDialog extends JDialog {
         });
         autoConnectPanel.setVisible(Settings.getStartupBehavior() == Settings.StartupBehavior.AUTO_CONNECT);
 
-        // Placeholder for potentially more behavior options below
+        // Block select mode checkbox
         gbc.gridy = 2;
+        gbc.gridwidth = 2;
+        blockSelectCheck = new JCheckBox("Block selection mode (rectangular select)", Settings.getBlockSelectMode());
+        panel.add(blockSelectCheck, gbc);
+
+        // Placeholder for potentially more behavior options below
+        gbc.gridy = 3;
         gbc.weighty = 1.0;
         panel.add(Box.createGlue(), gbc);
 
@@ -204,6 +359,7 @@ public class SettingsDialog extends JDialog {
             Color init = org.pubvm.j3270.config.Settings.getColorOverride(i, TerminalPanel.DEFAULT_HOST_COLORS[i]);
             tempHostColors[i] = init;
             JPanel cb = new JPanel();
+            cb.setName("colorSwatch");
             cb.setBackground(init);
             cb.setPreferredSize(new Dimension(30, 30));
             cb.setBorder(new LineBorder(Color.DARK_GRAY));
@@ -238,6 +394,7 @@ public class SettingsDialog extends JDialog {
             JPanel p = new JPanel(new BorderLayout());
             p.add(new JLabel(mk, SwingConstants.CENTER), BorderLayout.NORTH);
             JPanel cb = new JPanel();
+            cb.setName("colorSwatch");
             cb.setBackground(init);
             cb.setPreferredSize(new Dimension(40, 40));
             cb.setBorder(new LineBorder(Color.DARK_GRAY));
@@ -331,6 +488,8 @@ public class SettingsDialog extends JDialog {
             captureDialog.setSize(320, 100);
             captureDialog.setLocationRelativeTo(this);
             JLabel lbl = new JLabel("Press any key combination now...", SwingConstants.CENTER);
+            lbl.setForeground(DARK_FG);
+            captureDialog.getContentPane().setBackground(DARK_BG);
             captureDialog.add(lbl);
             captureDialog.addKeyListener(new KeyAdapter() {
                 @Override
@@ -442,6 +601,8 @@ public class SettingsDialog extends JDialog {
         return action; // nav keys default to their own name
     }
 
+    // ========== Apply Settings ==========
+
     private boolean applySettings() {
         try {
             // Apply Appearance
@@ -464,6 +625,9 @@ public class SettingsDialog extends JDialog {
                 }
             }
 
+            // Block select mode
+            Settings.setBlockSelectMode(blockSelectCheck.isSelected());
+
             // Propagate visual changes to the app
             // Save Colors
             for (int i=0; i<16; i++) {
@@ -487,4 +651,43 @@ public class SettingsDialog extends JDialog {
             return false;
         }
     }
+
+    // ========== Export Config ==========
+
+    private void exportConfig() {
+        JFileChooser fc = new JFileChooser();
+        fc.setDialogTitle("Export Configuration");
+        fc.setSelectedFile(new java.io.File("j3270.ini"));
+        fc.setFileFilter(new javax.swing.filechooser.FileNameExtensionFilter("INI Files (*.ini)", "ini"));
+
+        int result = fc.showSaveDialog(this);
+        if (result == JFileChooser.APPROVE_OPTION) {
+            java.io.File file = fc.getSelectedFile();
+            // Ensure .ini extension
+            if (!file.getName().toLowerCase().endsWith(".ini")) {
+                file = new java.io.File(file.getAbsolutePath() + ".ini");
+            }
+
+            // Confirm overwrite
+            if (file.exists()) {
+                int confirm = JOptionPane.showConfirmDialog(this,
+                    "File already exists. Overwrite?", "Confirm Overwrite",
+                    JOptionPane.YES_NO_OPTION);
+                if (confirm != JOptionPane.YES_OPTION) return;
+            }
+
+            try {
+                // Apply current dialog state first so the export reflects latest changes
+                applySettings();
+                Settings.exportToIniFile(file.getAbsolutePath());
+                JOptionPane.showMessageDialog(this,
+                    "Configuration exported to:\n" + file.getAbsolutePath(),
+                    "Export Successful", JOptionPane.INFORMATION_MESSAGE);
+            } catch (Exception ex) {
+                JOptionPane.showMessageDialog(this,
+                    "Export failed: " + ex.getMessage(),
+                    "Export Error", JOptionPane.ERROR_MESSAGE);
+            }
+        }
+    }
 }

j3270/src/main/java/org/pubvm/j3270/ui/TerminalPanel.java

@@ -6,6 +6,7 @@ import org.lib3270j.screen.ScreenBuffer;
 
 import javax.swing.*;
 import java.awt.*;
+import java.awt.datatransfer.*;
 import java.awt.event.*;
 
 import static org.lib3270j.protocol.DS3270Constants.*;
@@ -44,6 +45,39 @@ public class TerminalPanel extends JPanel {
     // Background
     private Color bgColor;
 
+    // ========== Selection / Copy-Paste state ==========
+    private boolean blockSelectMode = false;
+    private int selectionStartRow = -1, selectionStartCol = -1;
+    private int selectionEndRow = -1, selectionEndCol = -1;
+    private boolean isDragging = false;
+    private static final Color SELECTION_COLOR = new Color(75, 110, 175, 100);
+
+    // ========== Resize guard ==========
+    private boolean resizeGuard = false;
+
+    /**
+     * Compute the horizontal render offset to center the grid within the panel.
+     * Any leftover pixels (from integer font sizing) are split evenly.
+     */
+    private int getRenderOffsetX() {
+        int termCols = 80;
+        if (client != null) termCols = client.getScreenBuffer().getCols();
+        int gridW = termCols * cellWidth;
+        int extra = getWidth() - gridW;
+        return Math.max(padding, extra / 2);
+    }
+
+    /**
+     * Compute the vertical render offset to center the grid within the panel.
+     */
+    private int getRenderOffsetY() {
+        int termRows = 24;
+        if (client != null) termRows = client.getScreenBuffer().getRows();
+        int gridH = termRows * cellHeight;
+        int extra = getHeight() - gridH;
+        return Math.max(padding, extra / 2);
+    }
+
     // Default Host color mapping
     public static final Color[] DEFAULT_HOST_COLORS = {
             new Color(0, 0, 0), // 0: Neutral Black
@@ -87,22 +121,313 @@ public class TerminalPanel extends JPanel {
         setupFont();
         setupCursorBlink();
 
-        // Handle mouse clicks to position cursor and grab focus
+        blockSelectMode = org.pubvm.j3270.config.Settings.getBlockSelectMode();
-        addMouseListener(new MouseAdapter() {
+
+        // Handle mouse clicks to position cursor, selection, and grab focus
+        MouseAdapter mouseHandler = new MouseAdapter() {
             @Override
             public void mousePressed(MouseEvent e) {
                 requestFocusInWindow();
+
+                // Right-click context menu
+                if (SwingUtilities.isRightMouseButton(e)) {
+                    showContextMenu(e);
+                    return;
+                }
+
                 if (client != null && client.getConnectionState().isFullSession()) {
-                    int col = (e.getX() - padding) / cellWidth;
-                    int row = (e.getY() - padding) / cellHeight;
                     ScreenBuffer sb = client.getScreenBuffer();
-                    if (row >= 0 && row < sb.getRows() && col >= 0 && col < sb.getCols()) {
+                    int ox = getRenderOffsetX();
-                        sb.setCursorAddress(row * sb.getCols() + col);
+                    int oy = getRenderOffsetY();
-                        repaint();
+                    int col = (e.getX() - ox) / cellWidth;
+                    int row = (e.getY() - oy) / cellHeight;
+                    col = Math.max(0, Math.min(col, sb.getCols() - 1));
+                    row = Math.max(0, Math.min(row, sb.getRows() - 1));
+
+                    // Start selection
+                    selectionStartRow = row;
+                    selectionStartCol = col;
+                    selectionEndRow = row;
+                    selectionEndCol = col;
+                    isDragging = true;
+                    repaint();
+                }
+            }
+
+            @Override
+            public void mouseDragged(MouseEvent e) {
+                if (isDragging && client != null && client.getConnectionState().isFullSession()) {
+                    ScreenBuffer sb = client.getScreenBuffer();
+                    int ox = getRenderOffsetX();
+                    int oy = getRenderOffsetY();
+                    int col = (e.getX() - ox) / cellWidth;
+                    int row = (e.getY() - oy) / cellHeight;
+                    col = Math.max(0, Math.min(col, sb.getCols() - 1));
+                    row = Math.max(0, Math.min(row, sb.getRows() - 1));
+
+                    selectionEndRow = row;
+                    selectionEndCol = col;
+                    repaint();
+                }
+            }
+
+            @Override
+            public void mouseReleased(MouseEvent e) {
+                if (isDragging) {
+                    isDragging = false;
+                    // If start == end, treat as a click (position cursor, clear selection)
+                    if (selectionStartRow == selectionEndRow && selectionStartCol == selectionEndCol) {
+                        if (client != null && client.getConnectionState().isFullSession()) {
+                            ScreenBuffer sb = client.getScreenBuffer();
+                            sb.setCursorAddress(selectionStartRow * sb.getCols() + selectionStartCol);
+                            clearSelection();
+                        }
+                    }
+                    repaint();
+                }
+            }
+        };
+        addMouseListener(mouseHandler);
+        addMouseMotionListener(mouseHandler);
+
+        // Handle resize: auto-fit font to window size
+        addComponentListener(new ComponentAdapter() {
+            @Override
+            public void componentResized(ComponentEvent e) {
+                if (resizeGuard) return;
+                autoFitFont();
+            }
+        });
+    }
+
+    // ========== Selection / Copy-Paste ==========
+
+    private void clearSelection() {
+        selectionStartRow = -1;
+        selectionStartCol = -1;
+        selectionEndRow = -1;
+        selectionEndCol = -1;
+    }
+
+    private boolean hasSelection() {
+        return selectionStartRow >= 0 && selectionEndRow >= 0 &&
+               !(selectionStartRow == selectionEndRow && selectionStartCol == selectionEndCol);
+    }
+
+    /**
+     * Get the selected text from the screen buffer.
+     * In block mode: rectangular selection with newlines between rows.
+     * In line mode: stream selection, flowing left-to-right, top-to-bottom.
+     */
+    public String getSelectedText() {
+        if (!hasSelection() || client == null) return "";
+        ScreenBuffer sb = client.getScreenBuffer();
+        int cols = sb.getCols();
+
+        int r1 = Math.min(selectionStartRow, selectionEndRow);
+        int r2 = Math.max(selectionStartRow, selectionEndRow);
+        int c1, c2;
+
+        if (blockSelectMode) {
+            // Block mode: rectangular selection
+            c1 = Math.min(selectionStartCol, selectionEndCol);
+            c2 = Math.max(selectionStartCol, selectionEndCol);
+
+            StringBuilder result = new StringBuilder();
+            for (int r = r1; r <= r2; r++) {
+                if (r > r1) result.append('\n');
+                for (int c = c1; c <= c2; c++) {
+                    int baddr = r * cols + c;
+                    ExtendedAttribute ea = sb.getCell(baddr);
+                    char ch = ea.ucs4;
+                    if (ea.isFieldAttribute() || ch <= 0x20 || ch == 0xFF) {
+                        result.append(' ');
+                    } else {
+                        result.append(ch);
                     }
                 }
             }
+            return result.toString();
+        } else {
+            // Line/stream mode: flow from start to end
+            int startAddr, endAddr;
+            if (selectionStartRow < selectionEndRow ||
+                (selectionStartRow == selectionEndRow && selectionStartCol <= selectionEndCol)) {
+                startAddr = selectionStartRow * cols + selectionStartCol;
+                endAddr = selectionEndRow * cols + selectionEndCol;
+            } else {
+                startAddr = selectionEndRow * cols + selectionEndCol;
+                endAddr = selectionStartRow * cols + selectionStartCol;
+            }
+
+            StringBuilder result = new StringBuilder();
+            int prevRow = startAddr / cols;
+            for (int addr = startAddr; addr <= endAddr; addr++) {
+                int curRow = addr / cols;
+                if (curRow != prevRow) {
+                    result.append('\n');
+                    prevRow = curRow;
+                }
+                ExtendedAttribute ea = sb.getCell(addr);
+                char ch = ea.ucs4;
+                if (ea.isFieldAttribute() || ch <= 0x20 || ch == 0xFF) {
+                    result.append(' ');
+                } else {
+                    result.append(ch);
+                }
+            }
+            return result.toString();
+        }
+    }
+
+    private void copySelection() {
+        String text = getSelectedText();
+        if (!text.isEmpty()) {
+            StringSelection ss = new StringSelection(text);
+            Toolkit.getDefaultToolkit().getSystemClipboard().setContents(ss, null);
+        }
+    }
+
+    private void pasteClipboard() {
+        if (client == null || !client.getConnectionState().isFullSession()) return;
+        try {
+            String text = (String) Toolkit.getDefaultToolkit().getSystemClipboard()
+                .getData(DataFlavor.stringFlavor);
+            if (text != null) {
+                for (char ch : text.toCharArray()) {
+                    if (ch == '\n' || ch == '\r') {
+                        // Skip newlines in paste — user may paste multi-line text
+                        // but 3270 fields don't wrap the same way
+                        continue;
+                    }
+                    if (ch >= 0x20 && ch != 0x7F) {
+                        client.typeCharacter(ch);
+                    }
+                }
+                refreshScreen();
+            }
+        } catch (Exception ex) {
+            // Clipboard not available or wrong type — silently ignore
+        }
+    }
+
+    private void showContextMenu(MouseEvent e) {
+        JPopupMenu popup = new JPopupMenu();
+
+        JMenuItem copyItem = new JMenuItem("Copy");
+        copyItem.setEnabled(hasSelection());
+        copyItem.addActionListener(ev -> copySelection());
+        popup.add(copyItem);
+
+        JMenuItem pasteItem = new JMenuItem("Paste");
+        pasteItem.setEnabled(client != null && client.getConnectionState().isFullSession());
+        pasteItem.addActionListener(ev -> pasteClipboard());
+        popup.add(pasteItem);
+
+        popup.addSeparator();
+
+        JCheckBoxMenuItem blockModeItem = new JCheckBoxMenuItem("Block Select Mode", blockSelectMode);
+        blockModeItem.addActionListener(ev -> {
+            blockSelectMode = blockModeItem.isSelected();
+            org.pubvm.j3270.config.Settings.setBlockSelectMode(blockSelectMode);
         });
+        popup.add(blockModeItem);
+
+        popup.show(this, e.getX(), e.getY());
+    }
+
+    private boolean isCellSelected(int row, int col) {
+        if (!hasSelection()) return false;
+
+        int r1 = Math.min(selectionStartRow, selectionEndRow);
+        int r2 = Math.max(selectionStartRow, selectionEndRow);
+
+        if (blockSelectMode) {
+            int c1 = Math.min(selectionStartCol, selectionEndCol);
+            int c2 = Math.max(selectionStartCol, selectionEndCol);
+            return row >= r1 && row <= r2 && col >= c1 && col <= c2;
+        } else {
+            // Stream mode
+            int cols = 80;
+            if (client != null) cols = client.getScreenBuffer().getCols();
+            int addr = row * cols + col;
+            int startAddr, endAddr;
+            if (selectionStartRow < selectionEndRow ||
+                (selectionStartRow == selectionEndRow && selectionStartCol <= selectionEndCol)) {
+                startAddr = selectionStartRow * cols + selectionStartCol;
+                endAddr = selectionEndRow * cols + selectionEndCol;
+            } else {
+                startAddr = selectionEndRow * cols + selectionEndCol;
+                endAddr = selectionStartRow * cols + selectionStartCol;
+            }
+            return addr >= startAddr && addr <= endAddr;
+        }
+    }
+
+    // ========== Font auto-resize ==========
+
+    /**
+     * Auto-fit the font size to fill the current panel dimensions
+     * while respecting the terminal model's character grid.
+     * Any leftover pixels are handled by centering the grid
+     * (see getRenderOffsetX/Y).
+     */
+    private void autoFitFont() {
+        int panelW = getWidth();
+        int panelH = getHeight();
+        if (panelW <= 0 || panelH <= 0) return;
+
+        int termCols = 80;
+        int termRows = 24;
+        if (client != null) {
+            ScreenBuffer sb = client.getScreenBuffer();
+            termCols = sb.getCols();
+            termRows = sb.getRows();
+        }
+
+        // Use minimal padding for the fit calculation
+        int availW = panelW - 2 * padding;
+        int availH = panelH - 2 * padding;
+        if (availW <= 0 || availH <= 0) return;
+
+        // Find the largest font size where the grid fits
+        int bestSize = 8;
+        for (int testSize = 8; testSize <= 72; testSize++) {
+            Font testFont = new Font(terminalFont.getFamily(), Font.PLAIN, testSize);
+            FontMetrics fm = getFontMetrics(testFont);
+            int testCellW = fm.charWidth('M');
+            int testCellH = fm.getHeight();
+
+            if (testCellW * termCols <= availW && testCellH * termRows <= availH) {
+                bestSize = testSize;
+            } else {
+                break;
+            }
+        }
+
+        if (bestSize != currentFontSize) {
+            currentFontSize = bestSize;
+            org.pubvm.j3270.config.Settings.setFontSize(bestSize);
+            terminalFont = new Font(terminalFont.getFamily(), Font.PLAIN, bestSize);
+            updateCellSize();
+        }
+        // No window snap — any leftover pixels are centered via getRenderOffsetX/Y
+        repaint();
+    }
+
+    /**
+     * Called by J3270App when it needs to pack the frame (screen size changed,
+     * connection established, etc.). Sets the resize guard to prevent
+     * autoFitFont from firing during the pack.
+     */
+    public void guardedPack() {
+        resizeGuard = true;
+        revalidate();
+        Container top = getTopLevelAncestor();
+        if (top instanceof java.awt.Window) {
+            ((java.awt.Window) top).pack();
+        }
+        SwingUtilities.invokeLater(() -> resizeGuard = false);
     }
 
     /**
@@ -167,6 +492,11 @@ public class TerminalPanel extends JPanel {
         // Clear
         bindKeyToMap(im, "CLEAR", org.pubvm.j3270.config.Settings.getKeyBinding("CLEAR", "alt C"));
 
+        // Copy/Paste bindings — Cmd+C / Cmd+V (macOS) or Ctrl+C / Ctrl+V (others)
+        int shortcutMask = Toolkit.getDefaultToolkit().getMenuShortcutKeyMaskEx();
+        im.put(KeyStroke.getKeyStroke(KeyEvent.VK_C, shortcutMask), "j3270-COPY");
+        im.put(KeyStroke.getKeyStroke(KeyEvent.VK_V, shortcutMask), "j3270-PASTE");
+
         // Create actions for all bound keys
         am.put("j3270-ENTER", createAction(this::handleEnter));
         am.put("j3270-ESCAPE", createAction(this::handleReset));
@@ -185,6 +515,10 @@ public class TerminalPanel extends JPanel {
         am.put("j3270-INSERT", createAction(this::handleInsert));
         am.put("j3270-CLEAR", createAction(this::handleClear));
 
+        // Copy/Paste actions
+        am.put("j3270-COPY", createAction(this::copySelection));
+        am.put("j3270-PASTE", createAction(this::pasteClipboard));
+
         for (int i = 1; i <= 24; i++) {
             final int pf = i;
             am.put("j3270-PF" + i, createAction(() -> handlePF(pf)));
@@ -365,6 +699,7 @@ public class TerminalPanel extends JPanel {
         setupColors();
         setupKeyBindings();
         setupFont();
+        blockSelectMode = org.pubvm.j3270.config.Settings.getBlockSelectMode();
         revalidate();
         repaint();
     }
@@ -374,6 +709,7 @@ public class TerminalPanel extends JPanel {
         org.pubvm.j3270.config.Settings.setFontSize(size);
         terminalFont = terminalFont.deriveFont((float) size);
         updateCellSize();
+        resizeGuard = true;
         revalidate();
         repaint();
     }
@@ -406,10 +742,11 @@ public class TerminalPanel extends JPanel {
     public Dimension getPreferredSize() {
         if (client != null) {
             ScreenBuffer sb = client.getScreenBuffer();
-            // Always size to the MAXIMUM (alternate) screen dimensions,
+            // Use the CURRENT screen dimensions (not max) to eliminate extra space.
-            // matching how x3270 works — the window shows the full model size
+            // When the host switches to alternate screen, onScreenSizeChanged fires
-            int displayCols = sb.getMaxCols();
+            // and the frame re-packs.
-            int displayRows = sb.getMaxRows();
+            int displayCols = sb.getCols();
+            int displayRows = sb.getRows();
             return new Dimension(displayCols * cellWidth + padding * 2,
                     displayRows * cellHeight + padding * 2);
         }
@@ -427,11 +764,14 @@ public class TerminalPanel extends JPanel {
         g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
         g2.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_LCD_HRGB);
 
-        // Manually clear the entire graphics bounds to ensure no ghosting on
+        // Clear entire panel with background color
-        // resize/clip
         g2.setColor(bgColor);
         g2.fillRect(0, 0, getWidth(), getHeight());
 
+        // Compute centered offsets for the grid
+        int ox = getRenderOffsetX();
+        int oy = getRenderOffsetY();
+
         ScreenBuffer sb = client.getScreenBuffer();
         int rows = sb.getRows();
         int cols = sb.getCols();
@@ -446,8 +786,8 @@ public class TerminalPanel extends JPanel {
                 int baddr = row * cols + col;
                 ExtendedAttribute ea = sb.getCell(baddr);
 
-                int x = padding + col * cellWidth;
+                int x = ox + col * cellWidth;
-                int y = padding + row * cellHeight;
+                int y = oy + row * cellHeight;
 
                 // Determine colors and attributes
                 Color fgColor;
@@ -462,6 +802,11 @@ public class TerminalPanel extends JPanel {
                     // Field attributes display as blanks
                     g2.setColor(this.bgColor);
                     g2.fillRect(x, y, cellWidth, cellHeight);
+                    // Selection highlight on field attribute cells too
+                    if (isCellSelected(row, col)) {
+                        g2.setColor(SELECTION_COLOR);
+                        g2.fillRect(x, y, cellWidth, cellHeight);
+                    }
                     continue;
                 }
 
@@ -493,6 +838,10 @@ public class TerminalPanel extends JPanel {
                 if (faIsZero(currentFA & 0xFF)) {
                     g2.setColor(this.bgColor);
                     g2.fillRect(x, y, cellWidth, cellHeight);
+                    if (isCellSelected(row, col)) {
+                        g2.setColor(SELECTION_COLOR);
+                        g2.fillRect(x, y, cellWidth, cellHeight);
+                    }
                     continue;
                 }
 
@@ -522,6 +871,12 @@ public class TerminalPanel extends JPanel {
                     g2.drawLine(x, y + cellHeight - fontDescent,
                             x + cellWidth - 1, y + cellHeight - fontDescent);
                 }
+
+                // Draw selection highlight
+                if (isCellSelected(row, col)) {
+                    g2.setColor(SELECTION_COLOR);
+                    g2.fillRect(x, y, cellWidth, cellHeight);
+                }
             }
         }
 
@@ -530,8 +885,8 @@ public class TerminalPanel extends JPanel {
             int curAddr = sb.getCursorAddress();
             int curRow = curAddr / cols;
             int curCol = curAddr % cols;
-            int cx = padding + curCol * cellWidth;
+            int cx = ox + curCol * cellWidth;
-            int cy = padding + curRow * cellHeight;
+            int cy = oy + curRow * cellHeight;
 
             g2.setColor(new Color(255, 255, 255, 180));
             g2.setXORMode(bgColor);

run.sh

@@ -39,6 +39,7 @@ echo "Executable JAR created at: $BUILD_DIR/j3270.jar"
 # ---------------------------------------------------------
 # Run the newly packaged JAR
 # ---------------------------------------------------------
-exec java -Dapple.laf.useScreenMenuBar=true \
+#exec java -Dapple.laf.useScreenMenuBar=true \
-          -Dapple.awt.application.name=j3270 \
+#          -Dapple.awt.application.name=j3270 \
-          -jar "$BUILD_DIR/j3270.jar" "$@"
+#          -jar "$BUILD_DIR/j3270.jar" "$@"
+nohup java -jar build/j3270.jar &