Index: src/org/openstreetmap/josm/Main.java
===================================================================
--- src/org/openstreetmap/josm/Main.java	(revision 45)
+++ src/org/openstreetmap/josm/Main.java	(revision 46)
@@ -4,4 +4,9 @@
 import java.awt.BorderLayout;
 import java.awt.Container;
+import java.awt.Dimension;
+import java.awt.Point;
+import java.awt.Toolkit;
+import java.util.Arrays;
+import java.util.Collection;
 
 import javax.swing.JFrame;
@@ -29,4 +34,5 @@
 import org.openstreetmap.josm.gui.ImageProvider;
 import org.openstreetmap.josm.gui.MapFrame;
+import org.openstreetmap.josm.gui.ShowModifiers;
 
 /**
@@ -74,5 +80,5 @@
 		getContentPane().add(panel, BorderLayout.CENTER);
 		setSize(1000,740); // some strange default size
-		setExtendedState(MAXIMIZED_BOTH); // some platform are able to maximize
+		setVisible(true);
 		
 		// creating actions
@@ -143,5 +149,5 @@
 		setupExceptionHandler();
 		setupUiDefaults();
-		
+
 		// load preferences
 		String errMsg = null;
@@ -170,4 +176,22 @@
 		main.setDefaultCloseOperation(EXIT_ON_CLOSE);
 		main.setVisible(true);
+
+		Collection<String> arguments = Arrays.asList(args);
+
+		if (arguments.contains("--show-modifiers")) {
+			Point p = main.getLocationOnScreen();
+			Dimension s = main.getSize();
+			new ShowModifiers(p.x + s.width - 3, p.y + s.height - 32);
+			main.setVisible(true);
+		}
+		
+		if (!arguments.contains("--no-fullscreen")) {
+			if (Toolkit.getDefaultToolkit().isFrameStateSupported(MAXIMIZED_BOTH))
+				main.setExtendedState(MAXIMIZED_BOTH); // some platform are able to maximize
+			else {
+				Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
+				main.setSize(d);
+			}
+		}
 	}
 
Index: src/org/openstreetmap/josm/gui/ShowModifiers.java
===================================================================
--- src/org/openstreetmap/josm/gui/ShowModifiers.java	(revision 46)
+++ src/org/openstreetmap/josm/gui/ShowModifiers.java	(revision 46)
@@ -0,0 +1,138 @@
+package org.openstreetmap.josm.gui;
+import java.awt.AWTEvent;
+import java.awt.Color;
+import java.awt.Dimension;
+import java.awt.Font;
+import java.awt.Graphics;
+import java.awt.GridLayout;
+import java.awt.Toolkit;
+import java.awt.event.AWTEventListener;
+import java.awt.event.InputEvent;
+import java.awt.event.KeyEvent;
+import java.awt.event.MouseEvent;
+import java.awt.event.MouseWheelEvent;
+
+import javax.swing.BorderFactory;
+import javax.swing.Box;
+import javax.swing.JComponent;
+import javax.swing.JFrame;
+import javax.swing.JLabel;
+import javax.swing.JPanel;
+
+public class ShowModifiers extends JFrame implements AWTEventListener, Runnable {
+
+	private JLabel ctrl, alt, shift;
+
+	private int mouseMod = -1;
+	private int wheelMod = 0;
+
+	public ShowModifiers(int x, int y) {
+		Toolkit.getDefaultToolkit().addAWTEventListener(this, 
+				AWTEvent.MOUSE_EVENT_MASK | AWTEvent.MOUSE_WHEEL_EVENT_MASK | AWTEvent.KEY_EVENT_MASK);
+
+		setDefaultCloseOperation(EXIT_ON_CLOSE);
+		setUndecorated(true);
+		setAlwaysOnTop(true);
+		Box v = Box.createHorizontalBox();
+		//v.add(mouse);
+		JComponent mouseSpace = new JLabel();
+		mouseSpace.setPreferredSize(new Dimension(63,103));
+		v.add(mouseSpace);
+		setContentPane(v);
+
+		JPanel p = new JPanel(new GridLayout(3,1));
+		v.add(p);
+		p.add(ctrl = createLabel("Ctrl"));
+		p.add(alt = createLabel("Alt"));
+		p.add(shift = createLabel("Shift"));
+		pack();
+		setLocation(x-getWidth(),y-getHeight());
+		setVisible(true);
+	}
+
+	private JLabel createLabel(String name) {
+		JLabel l = new JLabel(name);
+		l.setHorizontalAlignment(JLabel.CENTER);
+		l.setBorder(BorderFactory.createCompoundBorder(
+				BorderFactory.createLineBorder(Color.BLACK),
+				BorderFactory.createEmptyBorder(3,3,3,3)));
+		l.setFont(l.getFont().deriveFont(Font.PLAIN));
+		l.setOpaque(true);
+		return l;
+	}
+
+	public void eventDispatched(AWTEvent event) {
+		int keyMod = -1;
+		if (event instanceof InputEvent) {
+			InputEvent e = (InputEvent)event;
+			keyMod = e.getModifiersEx();
+			ctrl.setBackground((keyMod & KeyEvent.CTRL_DOWN_MASK) != 0 ? Color.RED : null);
+			alt.setBackground((keyMod & KeyEvent.ALT_DOWN_MASK) != 0 ? Color.RED : null);
+			shift.setBackground((keyMod & KeyEvent.SHIFT_DOWN_MASK) != 0 ? Color.RED : null);
+		}
+		if (event instanceof MouseWheelEvent) {
+			wheelMod = ((MouseWheelEvent)event).getWheelRotation();
+			repaint();
+		}
+		if (event instanceof MouseEvent) {
+			MouseEvent e = (MouseEvent)event;
+			mouseMod = e.getModifiersEx() & (MouseEvent.BUTTON1_DOWN_MASK | MouseEvent.BUTTON2_DOWN_MASK | MouseEvent.BUTTON3_DOWN_MASK);
+			repaint();
+		}
+		new Thread(this).start();
+	}
+
+	public static void main(String[] args) {
+		new ShowModifiers(0,0);
+	}
+
+	public void run() {
+		try {Thread.sleep(250);} catch (InterruptedException e) {}
+		wheelMod = 0;
+		Graphics g = getGraphics();
+		if (g != null) {
+			paint(g);
+			g.dispose();
+		}
+	}
+	
+	private void paintMouse(Graphics g) {
+		g.setColor(getBackground());
+		g.fillRect(0,0,60,100);
+		g.setColor(Color.BLACK);
+		
+		g.drawLine(5,5,55,5);
+		g.drawLine(5,5,5,75);
+		g.drawLine(55,5,55,75);
+		g.drawArc(5,55,50,40,180,180);
+		
+		g.drawLine(5,30,55,30);
+		g.drawLine(25,5,25,30);
+		g.drawLine(35,5,35,30);
+		g.drawLine(25,12,35,12);
+		g.drawLine(25,23,35,23);
+		
+		if (mouseMod == -1)
+			return;
+		g.setColor(Color.RED);
+		if ((mouseMod & MouseEvent.BUTTON1_DOWN_MASK) != 0)
+			g.fillRect(6,6,19,24);
+		if ((mouseMod & MouseEvent.BUTTON2_DOWN_MASK) != 0)
+			g.fillRect(26,13,9,10);
+		if ((mouseMod & MouseEvent.BUTTON3_DOWN_MASK) != 0)
+			g.fillRect(36,6,19,24);
+		
+		if (wheelMod == 0)
+			return;
+		if (wheelMod < 0)
+			g.fillRect(26,6,9,6);
+		else
+			g.fillRect(26,24,9,6);
+	}
+
+	@Override
+	public void paint(Graphics g) {
+		super.paint(g);
+		paintMouse(g);
+	}
+}