Index: trunk/src/org/openstreetmap/josm/gui/dialogs/validator/ValidatorTreePanel.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/dialogs/validator/ValidatorTreePanel.java	(revision 14877)
+++ trunk/src/org/openstreetmap/josm/gui/dialogs/validator/ValidatorTreePanel.java	(revision 14878)
@@ -204,4 +204,8 @@
             rootNode.add(severityNode);
 
+            if (oldExpandedRows.contains(severity)) {
+                expandedPaths.add(new TreePath(new Object[] {rootNode, severityNode}));
+            }
+
             final Map<String, List<TestError>> errorsWithEmptyMessageByDescription = errorsByMessageDescription.get("");
             if (errorsWithEmptyMessageByDescription != null) {