diff --git a/modules/time-calc-app/src/main/java/org/nanoboot/utils/timecalc/app/TimeCalcApp.java b/modules/time-calc-app/src/main/java/org/nanoboot/utils/timecalc/app/TimeCalcApp.java
index a5f830f..4aa472d 100644
--- a/modules/time-calc-app/src/main/java/org/nanoboot/utils/timecalc/app/TimeCalcApp.java
+++ b/modules/time-calc-app/src/main/java/org/nanoboot/utils/timecalc/app/TimeCalcApp.java
@@ -16,7 +16,7 @@ import java.io.IOException;
 public class TimeCalcApp {
 
     public StringProperty visibilityProperty =
-            new StringProperty("timeCalcApp.visibilityReadWriteProperty",
+            new StringProperty("timeCalcApp.visibilityProperty",
                     Visibility.WEAKLY_COLORED.name());
     private long startNanoTime = 0l;
 
diff --git a/modules/time-calc-app/src/main/java/org/nanoboot/utils/timecalc/app/TimeCalcManager.java b/modules/time-calc-app/src/main/java/org/nanoboot/utils/timecalc/app/TimeCalcManager.java
index 48dd14a..156079b 100644
--- a/modules/time-calc-app/src/main/java/org/nanoboot/utils/timecalc/app/TimeCalcManager.java
+++ b/modules/time-calc-app/src/main/java/org/nanoboot/utils/timecalc/app/TimeCalcManager.java
@@ -56,7 +56,6 @@ public class TimeCalcManager {
     private final TimeHM startTime;
     private final TimeHM overtime;
     private final TimeHM endTime;
-    private final TimeCalcApp timeCalcApp;
     private boolean stopBeforeEnd = false;
     private final Time time = new Time();
     private final TimeCalcConfiguration timeCalcConfiguration =
@@ -64,7 +63,6 @@ public class TimeCalcManager {
 
     public TimeCalcManager(String startTimeIn, String overTimeIn,
             TimeCalcApp timeCalcApp) {
-        this.timeCalcApp = timeCalcApp;
         timeCalcConfiguration
                 .setFromTimeCalcProperties(TimeCalcProperties.getInstance());
         //        Utils.everythingHidden
@@ -101,6 +99,10 @@ public class TimeCalcManager {
         //window.add(weatherButton);
         window.addAll(configButton, commandButton, jokeButton, restartButton,
                 exitButton);
+        boolean onlyGreyOrNone = timeCalcConfiguration.visibilityOnlyGreyOrNoneEnabledProperty.isEnabled();
+        if(onlyGreyOrNone) {
+            timeCalcApp.visibilityProperty.setValue(Visibility.GRAY.name());
+        }
         window.addKeyListener(new KeyAdapter() {
             // Key Pressed method
             public void keyPressed(KeyEvent e) {
@@ -108,7 +110,7 @@ public class TimeCalcManager {
                         .valueOf(timeCalcApp.visibilityProperty.getValue());
                 if (e.getKeyCode() == KeyEvent.VK_UP) {
                     timeCalcApp.visibilityProperty
-                            .setValue(Visibility.STRONGLY_COLORED.name());
+                            .setValue(onlyGreyOrNone ? Visibility.GRAY.name() : Visibility.STRONGLY_COLORED.name());
                 }
                 if (e.getKeyCode() == KeyEvent.VK_DOWN) {
                     timeCalcApp.visibilityProperty
@@ -117,14 +119,14 @@ public class TimeCalcManager {
                 if (e.getKeyCode() == KeyEvent.VK_H) {
                     if (visibility.isNone()) {
                         timeCalcApp.visibilityProperty
-                                .setValue(Visibility.STRONGLY_COLORED.name());
+                                .setValue(onlyGreyOrNone ? Visibility.GRAY.name() : Visibility.STRONGLY_COLORED.name());
                     } else {
                         timeCalcApp.visibilityProperty
                                 .setValue(Visibility.NONE.name());
                     }
                 }
                 if (e.getKeyCode() == KeyEvent.VK_G) {
-                    if (visibility.isGray()) {
+                    if (visibility.isGray() && !onlyGreyOrNone) {
                         timeCalcApp.visibilityProperty
                                 .setValue(Visibility.WEAKLY_COLORED.name());
                     } else {
@@ -134,18 +136,25 @@ public class TimeCalcManager {
                 }
 
                 if (e.getKeyCode() == KeyEvent.VK_C) {
-                    if (visibility.isStronglyColored()) {
-                        timeCalcApp.visibilityProperty
-                                .setValue(Visibility.WEAKLY_COLORED.name());
-                    } else {
-                        timeCalcApp.visibilityProperty
-                                .setValue(Visibility.STRONGLY_COLORED.name());
+                    if(!onlyGreyOrNone) {
+                        if (visibility.isStronglyColored()) {
+                            timeCalcApp.visibilityProperty
+                                    .setValue(Visibility.WEAKLY_COLORED.name());
+                        } else {
+                            timeCalcApp.visibilityProperty
+                                    .setValue(
+                                            Visibility.STRONGLY_COLORED.name());
+                        }
+                    }
+                    else {
+                        timeCalcApp.visibilityProperty.setValue(Visibility.GRAY
+                                .name());
                     }
                 }
                 if (e.getKeyCode() == KeyEvent.VK_V) {
                     if (visibility.isNone()) {
                         timeCalcApp.visibilityProperty
-                                .setValue(Visibility.STRONGLY_COLORED.name());
+                                .setValue(onlyGreyOrNone ? Visibility.GRAY.name() : Visibility.STRONGLY_COLORED.name());
                     } else {
                         timeCalcApp.visibilityProperty
                                 .setValue(Visibility.NONE.name());
@@ -154,7 +163,7 @@ public class TimeCalcManager {
                 if (e.getKeyCode() == KeyEvent.VK_SPACE) {
                     if (visibility.isStronglyColored()) {
                         timeCalcApp.visibilityProperty
-                                .setValue(Visibility.WEAKLY_COLORED.name());
+                                .setValue(onlyGreyOrNone ? Visibility.GRAY.name() : Visibility.WEAKLY_COLORED.name());
                     }
                     if (visibility.isWeaklyColored()) {
                         timeCalcApp.visibilityProperty
@@ -166,7 +175,7 @@ public class TimeCalcManager {
                     }
                     if (visibility.isNone()) {
                         timeCalcApp.visibilityProperty
-                                .setValue(Visibility.STRONGLY_COLORED.name());
+                                .setValue(onlyGreyOrNone ? Visibility.GRAY.name() : Visibility.STRONGLY_COLORED.name());
                     }
                 }
                 if (e.getKeyCode() == KeyEvent.VK_R) {
diff --git a/modules/time-calc-app/src/main/java/org/nanoboot/utils/timecalc/utils/property/Property.java b/modules/time-calc-app/src/main/java/org/nanoboot/utils/timecalc/utils/property/Property.java
index a335bfd..54e62be 100644
--- a/modules/time-calc-app/src/main/java/org/nanoboot/utils/timecalc/utils/property/Property.java
+++ b/modules/time-calc-app/src/main/java/org/nanoboot/utils/timecalc/utils/property/Property.java
@@ -20,6 +20,7 @@ public class Property<T> {
             new ArrayList<>();
     private final List<ChangeListener<T>>
             changeListeners = new ArrayList<ChangeListener<T>>();
+    private ChangeListener<T> boundChangeListener = null;
 
     public Property(String name, T valueIn) {
         this.name = name;
@@ -43,17 +44,21 @@ public class Property<T> {
             throw new TimeCalcException("No bound property");
         }
         this.value = boundToProperty.value;
+        this.boundToProperty.removeListener(this.boundChangeListener);
+        this.boundChangeListener = null;
         this.boundToProperty = null;
     }
 
     public void bindTo(Property<T> anotherProperty) {
         this.boundToProperty = anotherProperty;
-        this.boundToProperty
-                .addListener((Property<T> p, T oldValue, T newValue) -> {
+        this.boundChangeListener =
+                (Property<T> p, T oldValue, T newValue) -> {
                     this.markInvalid();
                     this.fireValueChangedEvent(oldValue);
                     //System.out.println("bindTo markInvalid " + p.getName() + " " + p.getValue());
-                });
+                };
+        this.boundToProperty
+                .addListener(boundChangeListener);
     }
 
     public T getValue() {
@@ -101,4 +106,8 @@ public class Property<T> {
         this.changeListeners.add(listener);
     }
 
+    public void removeListener(ChangeListener<T> listener) {
+        this.changeListeners.remove(listener);
+    }
+
 }
diff --git a/timecalc.conf b/timecalc.conf
index acbed06..4e8c5e8 100644
--- a/timecalc.conf
+++ b/timecalc.conf
@@ -4,7 +4,7 @@ clock.hands.second.enabled=true
 clock.hands.millisecond.enabled=false
 battery.waves.enabled=true
 default-visibility=STRONGLY_COLORED
-visibility.only-grey-or-none.enabled=false
+visibility.only-grey-or-none.enabled=true
 jokes.enabled=true
 commands.enabled=true
 toasts.enabled=true