Index: /trunk/src/org/openstreetmap/josm/gui/dialogs/layer/LayerVisibilityAction.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/gui/dialogs/layer/LayerVisibilityAction.java	(revision 15659)
+++ /trunk/src/org/openstreetmap/josm/gui/dialogs/layer/LayerVisibilityAction.java	(revision 15660)
@@ -34,4 +34,5 @@
 import javax.swing.JPopupMenu;
 import javax.swing.JSlider;
+import javax.swing.SwingUtilities;
 import javax.swing.UIManager;
 import javax.swing.border.Border;
@@ -63,5 +64,9 @@
      */
     private static final int SLIDER_WHEEL_INCREMENT = 5;
+    private static final double DEFAULT_OPACITY = 1;
+    private static final double DEFAULT_GAMMA_VALUE = 0;
+    private static final double DEFAULT_SHARPNESS_FACTOR = 1;
     private static final double MAX_SHARPNESS_FACTOR = 2;
+    private static final double DEFAULT_COLORFUL_FACTOR = 1;
     private static final double MAX_COLORFUL_FACTOR = 2;
     private final LayerListModel model;
@@ -231,7 +236,8 @@
          * @param minValue The minimum value to map to the left side.
          * @param maxValue The maximum value to map to the right side.
+         * @param defaultValue The default value for resetting.
          * @param layerClassFilter The type of layer influenced by this filter.
          */
-        AbstractFilterSlider(double minValue, double maxValue, Class<T> layerClassFilter) {
+        AbstractFilterSlider(double minValue, double maxValue, double defaultValue, Class<T> layerClassFilter) {
             super(new GridBagLayout());
             this.minValue = minValue;
@@ -251,4 +257,12 @@
 
             slider.addChangeListener(e -> onStateChanged());
+            slider.addMouseListener(new MouseAdapter() {
+                @Override
+                public void mouseClicked(MouseEvent e) {
+                    if (e != null && SwingUtilities.isLeftMouseButton(e) && e.getClickCount() > 1) {
+                        setRealValue(defaultValue);
+                    }
+                }
+            });
 
             //final NumberFormat format = DecimalFormat.getInstance();
@@ -352,7 +366,7 @@
          */
         OpacitySlider() {
-            super(0, 1, Layer.class);
+            super(0, 1, DEFAULT_OPACITY, Layer.class);
             setLabels("0%", "50%", "100%");
-            slider.setToolTipText(tr("Adjust opacity of the layer."));
+            slider.setToolTipText(tr("Adjust opacity of the layer.") + " " + tr("Double click to reset."));
         }
 
@@ -425,7 +439,7 @@
          */
         GammaFilterSlider() {
-            super(-1, 1, ImageryLayer.class);
+            super(-1, 1, DEFAULT_GAMMA_VALUE, ImageryLayer.class);
             setLabels("0", "1", "∞");
-            slider.setToolTipText(tr("Adjust gamma value of the layer."));
+            slider.setToolTipText(tr("Adjust gamma value of the layer.") + " " + tr("Double click to reset."));
         }
 
@@ -485,7 +499,7 @@
          */
         SharpnessSlider() {
-            super(0, MAX_SHARPNESS_FACTOR, ImageryLayer.class);
+            super(0, MAX_SHARPNESS_FACTOR, DEFAULT_SHARPNESS_FACTOR, ImageryLayer.class);
             setLabels(trc("image sharpness", "blurred"), trc("image sharpness", "normal"), trc("image sharpness", "sharp"));
-            slider.setToolTipText(tr("Adjust sharpness/blur value of the layer."));
+            slider.setToolTipText(tr("Adjust sharpness/blur value of the layer.") + " " + tr("Double click to reset."));
         }
 
@@ -523,7 +537,7 @@
          */
         ColorfulnessSlider() {
-            super(0, MAX_COLORFUL_FACTOR, ImageryLayer.class);
+            super(0, MAX_COLORFUL_FACTOR, DEFAULT_COLORFUL_FACTOR, ImageryLayer.class);
             setLabels(trc("image colorfulness", "less"), trc("image colorfulness", "normal"), trc("image colorfulness", "more"));
-            slider.setToolTipText(tr("Adjust colorfulness of the layer."));
+            slider.setToolTipText(tr("Adjust colorfulness of the layer.") + " " + tr("Double click to reset."));
         }