Index: trunk/src/org/openstreetmap/josm/gui/dialogs/layer/LayerVisibilityAction.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/dialogs/layer/LayerVisibilityAction.java	(revision 11222)
+++ trunk/src/org/openstreetmap/josm/gui/dialogs/layer/LayerVisibilityAction.java	(revision 11223)
@@ -204,5 +204,5 @@
                 return;
             }
-            double rotation = e.getPreciseWheelRotation();
+            double rotation = -1 * e.getPreciseWheelRotation();
             double destinationValue = getValue() + rotation * SLIDER_WHEEL_INCREMENT;
             if (rotation < 0) {
@@ -282,10 +282,9 @@
         @Override
         protected void mouseWheelMoved(MouseWheelEvent e) {
-            if (!isEnabled() && !filterLayers(model.getSelectedLayers()).isEmpty() && e.getPreciseWheelRotation() > 0) {
+            if (!isEnabled() && !filterLayers(model.getSelectedLayers()).isEmpty() && e.getPreciseWheelRotation() < 0) {
                 // make layer visible and set the value.
                 // this allows users to use the mouse wheel to make the layer visible if it was hidden previously.
                 e.consume();
                 setVisibleFlag(true);
-                setRealValue(0.05);
             } else {
                 super.mouseWheelMoved(e);