Index: trunk/src/org/openstreetmap/josm/gui/preferences/imagery/AddWMSLayerPanel.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/preferences/imagery/AddWMSLayerPanel.java	(revision 17656)
+++ trunk/src/org/openstreetmap/josm/gui/preferences/imagery/AddWMSLayerPanel.java	(revision 17657)
@@ -207,8 +207,13 @@
             return false;
         }
+        if (!endpoint.isSelected() && !getWmsUrl().isEmpty()) {
+            // if endpoint is not selected and imagery name and WMS URL is provided, allow adding imagery
+            // this is to cover the cases, when the user constructs URL on hers/his own
+            return true;
+        }
         /*
          * We need selection of the layers in following situations:
          * * endpoint is not selected (and we don't care about setDefault layers as it's disabled anyway)
-         * * endpoint is selected and setDefultLayers is selected
+         * * endpoint is selected and setDefaultLayers is selected
          */
         if ((!endpoint.isSelected() || setDefaultLayers.isSelected()) && (tree == null || tree.getSelectedLayers().isEmpty())) {