Index: /trunk/src/org/openstreetmap/josm/gui/util/AdvancedKeyPressDetector.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/gui/util/AdvancedKeyPressDetector.java	(revision 7219)
+++ /trunk/src/org/openstreetmap/josm/gui/util/AdvancedKeyPressDetector.java	(revision 7219)
@@ -0,0 +1,164 @@
+// License: GPL. For details, see LICENSE file.
+package org.openstreetmap.josm.gui.util;
+
+import java.awt.AWTEvent;
+import java.awt.Component;
+import java.awt.KeyboardFocusManager;
+import java.awt.Toolkit;
+import java.awt.event.AWTEventListener;
+import java.awt.event.ActionEvent;
+import java.awt.event.ActionListener;
+import java.awt.event.KeyEvent;
+import java.util.ArrayList;
+import java.util.Set;
+import java.util.TreeSet;
+import javax.swing.JFrame;
+import javax.swing.SwingUtilities;
+import javax.swing.Timer;
+
+import org.openstreetmap.josm.Main;
+
+import static org.openstreetmap.josm.tools.I18n.tr;
+/**
+ * Helper object that allows cross-platform detection of key press and realease events
+ * instance is available globally as Main.map.keyDetector
+ * @since 7217
+ */
+public class AdvancedKeyPressDetector implements AWTEventListener {
+
+    // events for crossplatform key holding processing
+    // thanks to http://www.arco.in-berlin.de/keyevent.html
+    private final Set<Integer> set = new TreeSet<>();
+    private KeyEvent releaseEvent;
+    private Timer timer;
+
+    private final ArrayList<KeyPressReleaseListener> keyListeners = new ArrayList<>();
+    private final ArrayList<ModifierListener> modifierListeners = new ArrayList<>();
+    private int previousModifiers;
+
+    /**
+     * Adds an object that wants to receive key press and release events
+     */
+    public void addKeyListener(KeyPressReleaseListener l) {
+        keyListeners.add(l);
+    }
+
+    /**
+     * Adds an object that wants to receive key modifier changed events
+     */
+    public void addModifierListener(ModifierListener l) {
+        modifierListeners.add(l);
+    }
+
+    /**
+     * Removes the listener
+     */
+    public void removeKeyListener(KeyPressReleaseListener l) {
+        keyListeners.remove(l);
+    }
+
+    /**
+     * Removes the key modifier listener
+     */
+    public void removeModifierListener(ModifierListener l) {
+        modifierListeners.remove(l);
+    }
+
+
+    /**
+     * Register this object as AWTEventListener
+     */
+    public void register() {
+        try {
+            Toolkit.getDefaultToolkit().addAWTEventListener(this, AWTEvent.KEY_EVENT_MASK);
+        } catch (SecurityException ex) {
+            Main.warn(ex);
+        }
+        timer = new Timer(0, new ActionListener() {
+            @Override
+            public void actionPerformed(ActionEvent e) {
+                timer.stop();
+                if (set.remove(releaseEvent.getKeyCode())) {
+                    for (KeyPressReleaseListener q: keyListeners) {
+                        q.doKeyReleased(releaseEvent);
+                    }
+                }
+            }
+        });
+    }
+
+    /**
+     * Unregister this object as AWTEventListener
+     * lists of listeners are not cleared!
+     */
+    public void unregister() {
+        timer.stop(); set.clear();
+        if (!keyListeners.isEmpty()) {
+            Main.warn(tr("Some of the key listeners forgot to remove themselves: {0}"), keyListeners.toString());
+        }
+        if (!modifierListeners.isEmpty()) {
+            Main.warn(tr("Some of the key listeners forgot to remove themselves: {0}"), modifierListeners.toString());
+        }
+        try {
+            Toolkit.getDefaultToolkit().removeAWTEventListener(this);
+        } catch (SecurityException ex) {
+            Main.warn(ex);
+        }
+    }
+
+    private void processKeyEvent(KeyEvent e) {
+        if (e.getID() == KeyEvent.KEY_PRESSED) {
+            if (timer.isRunning()) {
+                timer.stop();
+            } else if (set.add((e.getKeyCode()))) {
+                for (KeyPressReleaseListener q: keyListeners) {
+                    q.doKeyPressed(e);
+                }
+            }
+        } else if (e.getID() == KeyEvent.KEY_RELEASED) {
+            if (timer.isRunning()) {
+                timer.stop();
+                if (set.remove(e.getKeyCode())) {
+                    for (KeyPressReleaseListener q: keyListeners) {
+                        q.doKeyReleased(e);
+                    }
+                }
+            } else {
+                releaseEvent = e;
+                timer.restart();
+            }
+        }
+    }
+
+    @Override
+    public void eventDispatched(AWTEvent e) {
+        if (!(e instanceof KeyEvent)) {
+            return;
+        }
+        KeyEvent ke = (KeyEvent) e;
+
+        // check if ctrl, alt, shift modifiers are changed
+        int modif = ke.getModifiers();
+        if (previousModifiers != modif) {
+            previousModifiers = modif;
+            for (ModifierListener m: modifierListeners) {
+                m.modifiersChanged(modif);
+            }
+        }
+
+        // check if key press is done in main window, not in dialogs
+        Component focused = KeyboardFocusManager.getCurrentKeyboardFocusManager().getFocusOwner();
+        if (SwingUtilities.getWindowAncestor(focused) instanceof JFrame) {
+            processKeyEvent(ke);
+        }
+    }
+
+    /**
+     * Allows to determine if the key with specific code is pressed now
+     * @param keyCode the key code, for example KeyEvent.VK_ENTER
+     * @return true if the key is pressed now
+     */
+    public boolean isKeyPressed(int keyCode) {
+        return set.contains(Integer.valueOf(keyCode));
+    }
+}
Index: /trunk/src/org/openstreetmap/josm/gui/util/KeyPressReleaseListener.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/gui/util/KeyPressReleaseListener.java	(revision 7219)
+++ /trunk/src/org/openstreetmap/josm/gui/util/KeyPressReleaseListener.java	(revision 7219)
@@ -0,0 +1,20 @@
+// License: GPL. For details, see LICENSE file.
+package org.openstreetmap.josm.gui.util;
+
+import java.awt.event.KeyEvent;
+
+/**
+ * Interface that is used to detect key pressing and releasing
+ */
+public interface KeyPressReleaseListener {
+    /**
+     * This is called when key press event is actually pressed
+     * (no fake events while holding key)
+     */
+    public void doKeyPressed(KeyEvent e);
+    /**
+     * This is called when key press event is actually released
+     * (no fake events while holding key)
+     */
+    public void doKeyReleased(KeyEvent e);
+}
Index: /trunk/src/org/openstreetmap/josm/gui/util/ModifierListener.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/gui/util/ModifierListener.java	(revision 7219)
+++ /trunk/src/org/openstreetmap/josm/gui/util/ModifierListener.java	(revision 7219)
@@ -0,0 +1,10 @@
+// License: GPL. For details, see LICENSE file.
+package org.openstreetmap.josm.gui.util;
+
+/**
+ * Listener called when pressed modifier keys change is detected
+ * @since 7217
+ */
+public interface ModifierListener {
+    public void modifiersChanged(int modifiers);
+}