add some rsys utils (mostly just linux modified)

src/main/java/com/rdesk/Main.java

@@ -8,6 +8,7 @@ import com.rdesk.applications.system.Exit;
 import com.rdesk.applications.productivity.Notes;
 import com.rdesk.applications.system.TaskManager;
 import com.rdesk.applications.system.filehaj.FileExplorerApp;
+import com.rdesk.applications.system.rsys.KbChanger;
 import com.rdesk.kernel.*;
 import com.rdesk.kernel.launcher.AppLauncher;
 
@@ -84,14 +85,17 @@ public class Main {
     }
 
     private static void registerSystemApps(AppLauncher launcher) {
-
+        // productivity
         launcher.addApp(new Notes(), "Productivity");
         launcher.addApp(new TabbedBrowser(), "Productivity");
         launcher.addApp(new CodeDesk(), "Productivity");
         launcher.addApp(new Calculator(), "Productivity");
+        // entertainment
         launcher.addApp(new Xkcd(), "Entertainment");
+        // System apps
         launcher.addApp(new Exit(),     "System");
         launcher.addApp(new TaskManager(), "System");
         launcher.addApp(new FileExplorerApp(), "System");
+        launcher.addApp(new KbChanger(), "System");
     }
 }

src/main/java/com/rdesk/applications/system/rsys/KbChanger.java

@@ -0,0 +1,94 @@
+package com.rdesk.applications.system.rsys;
+
+import com.rdesk.kernel.DesktopApp;
+import com.rdesk.kernel.Kernel;
+import com.rdesk.kernel.rsys.KbInterface;
+
+import javax.swing.*;
+import java.awt.*;
+import java.awt.event.ActionEvent;
+import java.awt.event.KeyAdapter;
+import java.awt.event.KeyEvent;
+
+public class KbChanger implements DesktopApp {
+    private static final String[] LAYOUTS = {
+            "us", "uk", "de", "fr", "es", "it", "ru", "jp", "br", "cz"
+    };
+
+    @Override
+    public String getId() {
+        return "kbchanger";
+    }
+
+    @Override
+    public String getName() {
+        return "KbChanger";
+    }
+
+    @Override
+    public JInternalFrame createWindow(Kernel kernel) {
+        JInternalFrame frame = new JInternalFrame(
+                "Keyboard Layout",
+                true, // resizable
+                true, // closable
+                true, // maximizable
+                true  // iconifiable
+        );
+
+        frame.setSize(420, 200);
+        frame.setLayout(new BorderLayout(8, 8));
+        frame.setDefaultCloseOperation(JFrame.HIDE_ON_CLOSE);
+
+        JPanel top = new JPanel(new FlowLayout(FlowLayout.LEFT, 8, 12));
+        top.add(new JLabel("Layout:"));
+
+        JComboBox<String> layoutCombo = new JComboBox<>(LAYOUTS);
+        layoutCombo.setEditable(false);
+        top.add(layoutCombo);
+
+        JButton applyBtn = new JButton("Apply");
+        top.add(applyBtn);
+
+        frame.add(top, BorderLayout.NORTH);
+
+        JPanel center = new JPanel(new BorderLayout(6, 6));
+        JLabel hint = new JLabel("Type here to test the selected layout:");
+        center.add(hint, BorderLayout.NORTH);
+
+        JTextField testField = new JTextField();
+        center.add(testField, BorderLayout.CENTER);
+
+        JLabel status = new JLabel("Last applied: (none)");
+        status.setBorder(BorderFactory.createEmptyBorder(6, 6, 6, 6));
+        center.add(status, BorderLayout.SOUTH);
+
+        frame.add(center, BorderLayout.CENTER);
+
+        KbInterface kb = new KbInterface();
+
+        applyBtn.addActionListener((ActionEvent e) -> {
+            String selected = (String) layoutCombo.getSelectedItem();
+            if (selected == null || selected.trim().isEmpty()) {
+                JOptionPane.showMessageDialog(frame, "Please select a layout.", "Keyboard Layout", JOptionPane.WARNING_MESSAGE);
+                return;
+            }
+
+            kb.setKbLayout(selected);
+
+            status.setText("Last applied: " + selected);
+            SwingUtilities.invokeLater(testField::requestFocusInWindow);
+        });
+
+        testField.addKeyListener(new KeyAdapter() {
+            @Override
+            public void keyPressed(KeyEvent e) {
+                if (e.getKeyCode() == KeyEvent.VK_ENTER) {
+                    applyBtn.doClick();
+                }
+            }
+        });
+
+        frame.setVisible(true);
+        return frame;
+    }
+}

src/main/java/com/rdesk/kernel/rsys/KbInterface.java

@@ -0,0 +1,80 @@
+
+package com.rdesk.kernel.rsys;
+
+import com.sun.jna.Library;
+import com.sun.jna.Native;
+import com.sun.jna.win32.W32APIOptions;
+
+import javax.swing.*;
+
+public class KbInterface {
+
+    private static final java.util.Map<String, String> LAYOUT_TO_KLID = java.util.Map.ofEntries(
+            java.util.Map.entry("us", "00000409"),
+            java.util.Map.entry("uk", "00000809"),
+            java.util.Map.entry("de", "00000407"),
+            java.util.Map.entry("fr", "0000040C"),
+            java.util.Map.entry("es", "0000040A"),
+            java.util.Map.entry("it", "00000410"),
+            java.util.Map.entry("ru", "00000419"),
+            java.util.Map.entry("jp", "00000411"),
+            java.util.Map.entry("br", "00000416"),
+            java.util.Map.entry("cz", "00000405")
+    );
+
+
+    private interface User32 extends Library {
+        User32 INSTANCE = Native.load("user32", User32.class, W32APIOptions.DEFAULT_OPTIONS);
+        long LoadKeyboardLayoutA(String pwszKLID, int Flags);
+    }
+
+    public void setKbLayout(String kbLayout) {
+        String os = System.getProperty("os.name").toLowerCase();
+        try {
+            if (os.contains("win")) {
+                setWindowsLayout(kbLayout);
+            } else if (os.contains("nix") || os.contains("nux") || os.contains("aix") || os.contains("linux")) {
+                setLinuxLayout(kbLayout);
+            } else if (os.contains("mac")) {
+                showError("mac is too shitty for this");
+            } else {
+                showError("what are you running?: " + os);
+            }
+        } catch (Exception ex) {
+            showError("The keyboard layout could not be set " + ex.getMessage());
+        }
+    }
+
+    private void setLinuxLayout(String kbLayout) throws Exception {
+        new ProcessBuilder("setxkbmap", kbLayout)
+                .inheritIO()
+                .start()
+                .waitFor();
+    }
+
+    private void setWindowsLayout(String kbLayout) {
+        String klid = kbLayout;
+        if (!kbLayout.matches("[0-9A-Fa-f]{8}")) {
+            klid = LAYOUT_TO_KLID.getOrDefault(kbLayout.toLowerCase(), null);
+            if (klid == null) {
+                showError("Unknown Windows layout: " + kbLayout);
+                return;
+            }
+        }
+
+        int KLF_ACTIVATE = 0x00000001;
+        long result = User32.INSTANCE.LoadKeyboardLayoutA(klid, KLF_ACTIVATE);
+        if (result == 0) {
+            showError("Failed to load keyboard layout " + klid);
+        }
+    }
+
+    private void showError(String message) {
+        JOptionPane.showMessageDialog(
+                null,
+                message,
+                "Keyboard Layout",
+                JOptionPane.ERROR_MESSAGE
+        );
+    }
+}