Index: trunk/src/org/openstreetmap/josm/gui/ExtendedDialog.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/ExtendedDialog.java	(revision 11103)
+++ trunk/src/org/openstreetmap/josm/gui/ExtendedDialog.java	(revision 11105)
@@ -108,5 +108,5 @@
     // For easy access when inherited
     protected transient Insets contentInsets = new Insets(10, 5, 0, 5);
-    protected List<JButton> buttons = new ArrayList<>();
+    protected transient List<JButton> buttons = new ArrayList<>();
 
     /**
Index: trunk/src/org/openstreetmap/josm/gui/dialogs/OsmIdSelectionDialog.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/dialogs/OsmIdSelectionDialog.java	(revision 11103)
+++ trunk/src/org/openstreetmap/josm/gui/dialogs/OsmIdSelectionDialog.java	(revision 11105)
@@ -13,7 +13,7 @@
 import java.util.Collection;
 import java.util.Collections;
+import java.util.EnumSet;
 import java.util.LinkedList;
 import java.util.List;
-import java.util.Set;
 import java.util.stream.Collectors;
 
@@ -206,5 +206,6 @@
                     .collect(Collectors.joining(", "));
             tfId.tryToPasteFrom(parsedText);
-            final Set<OsmPrimitiveType> types = ids.stream().map(SimplePrimitiveId::getType).collect(Collectors.toSet());
+            final EnumSet<OsmPrimitiveType> types = ids.stream().map(SimplePrimitiveId::getType).collect(
+                    Collectors.toCollection(() -> EnumSet.noneOf(OsmPrimitiveType.class)));
             if (types.size() == 1) {
                 // select corresponding type