Index: src/org/openstreetmap/josm/data/validation/OsmValidator.java
===================================================================
--- src/org/openstreetmap/josm/data/validation/OsmValidator.java	(revision 15456)
+++ src/org/openstreetmap/josm/data/validation/OsmValidator.java	(working copy)
@@ -313,8 +313,11 @@
         final Pattern elemId2Pattern = Pattern.compile("^[0-9]+$");
         for (Entry<String, String> e: ignoredErrors.entrySet()) {
             String key = e.getKey();
-            String value = e.getValue();
-            ArrayList<String> ignoredWayList = new ArrayList<>();
+            // key starts with a code, it maybe followed by a string (eg. a MapCSS rule) and
+            // optionally with a list of one or more OSM element IDs
+            String description = e.getValue();
+
+            ArrayList<String> ignoredElementList = new ArrayList<>();
             String[] osmobjects = elemId1Pattern.split(key);
             for (int i = 1; i < osmobjects.length; i++) {
                 String osmid = osmobjects[i];
@@ -323,10 +326,10 @@
                     int index = key.indexOf(osmid);
                     if (index < key.lastIndexOf(']')) continue;
                     char type = key.charAt(index - 1);
-                    ignoredWayList.add(type + osmid);
+                    ignoredElementList.add(type + osmid);
                 }
             }
-            for (String osmignore : ignoredWayList) {
+            for (String osmignore : ignoredElementList) {
                 key = key.replace(':' + osmignore, "");
             }
 
@@ -333,8 +336,8 @@
             DefaultMutableTreeNode trunk;
             DefaultMutableTreeNode branch;
 
-            if (value != null && !value.isEmpty()) {
-                trunk = inTree(root, value);
+            if (description != null && !description.isEmpty()) {
+                trunk = inTree(root, description);
                 branch = inTree(trunk, key);
                 trunk.add(branch);
             } else {
@@ -341,8 +344,16 @@
                 trunk = inTree(root, key);
                 branch = trunk;
             }
-            ignoredWayList.forEach(osmignore -> branch.add(new DefaultMutableTreeNode(osmignore)));
-
+            if (!ignoredElementList.isEmpty()) {
+                String item;
+                if (ignoredElementList.size() == 1) {
+                    item = ignoredElementList.iterator().next();
+                } else {
+                    // combination of two or more objects, keep them together
+                    item = ignoredElementList.toString(); // [ID1, ID2, ..., IDn]
+                }
+                branch.add(new DefaultMutableTreeNode(item));
+            }
             root.add(trunk);
         }
         return new JTree(root);
@@ -377,37 +388,46 @@
     private static Map<String, String> buildIgnore(TreeModel model, DefaultMutableTreeNode node) {
         HashMap<String, String> rHashMap = new HashMap<>();
 
-        String osmids = node.getUserObject().toString();
-        String description = "";
-
-        if (!model.getRoot().equals(node)) {
-            description = ((DefaultMutableTreeNode) node.getParent()).getUserObject().toString();
-        } else {
-            description = node.getUserObject().toString();
-        }
-        if (tr("Ignore list").equals(description)) description = "";
-        if (!osmids.matches("^[0-9]+(_.*|$)")) {
-            description = osmids;
-            osmids = "";
-        }
-
-
-        StringBuilder sb = new StringBuilder();
         for (int i = 0; i < model.getChildCount(node); i++) {
             DefaultMutableTreeNode child = (DefaultMutableTreeNode) model.getChild(node, i);
             if (model.getChildCount(child) == 0) {
-                String ignoreName = child.getUserObject().toString();
-                if (ignoreName.matches("^(r|w|n)_.*")) {
-                    sb.append(':').append(child.getUserObject().toString());
-                } else if (ignoreName.matches("^[0-9]+(_.*|)$")) {
-                    rHashMap.put(ignoreName, description);
+                // create an entry for the error list
+                String key = node.getUserObject().toString();
+                String description;
+
+                if (!model.getRoot().equals(node)) {
+                    description = ((DefaultMutableTreeNode) node.getParent()).getUserObject().toString();
+                } else {
+                    description = key; // we get here when reading old file ignorederrors
                 }
+                if (tr("Ignore list").equals(description))
+                    description = "";
+                if (!key.matches("^[0-9]+(_.*|$)")) {
+                    description = key;
+                    key = "";
+                }
+
+                String item = child.getUserObject().toString();
+                String entry = null;
+                if (item.matches("^\\[(r|w|n)_.*")) {
+                    // list of elements (produced with list.toString() method)
+                    entry = key + ":" + item.substring(1, item.lastIndexOf(']')).replace(", ", ":");
+                } else if (item.matches("^(r|w|n)_.*")) {
+                    // single element
+                    entry = key + ":" + item;
+                } else if (item.matches("^[0-9]+(_.*|)$")) {
+                    // no element ids
+                    entry = item;
+                }
+                if (entry != null) {
+                    rHashMap.put(entry, description);
+                } else {
+                    Logging.warn("ignored unexpected item in validator ignore list management dialog:'" + item + "'");
+                }
             } else {
                 rHashMap.putAll(buildIgnore(model, child));
             }
         }
-        osmids += sb.toString();
-        if (!osmids.isEmpty() && osmids.indexOf(':') != 0) rHashMap.put(osmids, description);
         return rHashMap;
     }