Index: RelationListDialog.java
===================================================================
--- RelationListDialog.java	(revision 5727)
+++ RelationListDialog.java	(working copy)
@@ -916,8 +915,8 @@
                 resetFilter();
             }
             for (Relation r: sel) {
-                int i = getVisibleRelationIndex(r);
-                if (i<0) {
+                Integer i = getVisibleRelationIndex(r);
+                if (i== null || i<0) {
                     continue;
                 }
                 selectionModel.addSelectionInterval(i,i);