Index: /trunk/src/org/openstreetmap/josm/gui/dialogs/layer/LayerVisibilityAction.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/gui/dialogs/layer/LayerVisibilityAction.java	(revision 12392)
+++ /trunk/src/org/openstreetmap/josm/gui/dialogs/layer/LayerVisibilityAction.java	(revision 12393)
@@ -281,4 +281,5 @@
         public void updateLayers(List<Layer> layers, boolean allVisible, boolean allHidden) {
             Collection<? extends Layer> usedLayers = filterLayers(layers);
+            setVisible(!usedLayers.isEmpty());
             if (!usedLayers.stream().anyMatch(Layer::isVisible)) {
                 slider.setEnabled(false);