Index: trunk/src/org/openstreetmap/josm/gui/history/NodeListTableCellRenderer.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/history/NodeListTableCellRenderer.java	(revision 10016)
+++ trunk/src/org/openstreetmap/josm/gui/history/NodeListTableCellRenderer.java	(revision 10021)
@@ -55,5 +55,7 @@
             int row, int column) {
 
-        renderNode((TwoColumnDiff.Item) value, isSelected);
+        if (value != null) {
+            renderNode((TwoColumnDiff.Item) value, isSelected);
+        }
         return this;
     }
Index: trunk/src/org/openstreetmap/josm/gui/history/RelationMemberListTableCellRenderer.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/history/RelationMemberListTableCellRenderer.java	(revision 10016)
+++ trunk/src/org/openstreetmap/josm/gui/history/RelationMemberListTableCellRenderer.java	(revision 10021)
@@ -79,4 +79,5 @@
             int row, int column) {
 
+        if (value == null) return this;
         Item member = (TwoColumnDiff.Item) value;
         renderIcon((RelationMemberData) member.value);
Index: trunk/src/org/openstreetmap/josm/gui/history/VersionTable.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/history/VersionTable.java	(revision 10016)
+++ trunk/src/org/openstreetmap/josm/gui/history/VersionTable.java	(revision 10021)
@@ -319,4 +319,9 @@
         }
 
+        // for unit tests
+        private AlignedRenderer() {
+            this(SwingConstants.LEFT);
+        }
+
         @Override
         public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus,
Index: trunk/src/org/openstreetmap/josm/gui/io/LayerNameAndFilePathTableCell.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/io/LayerNameAndFilePathTableCell.java	(revision 10016)
+++ trunk/src/org/openstreetmap/josm/gui/io/LayerNameAndFilePathTableCell.java	(revision 10021)
@@ -85,4 +85,5 @@
             boolean hasFocus, int row, int column) {
         removeAll();
+        if (value == null) return this;
         SaveLayerInfo info = (SaveLayerInfo) value;
         StringBuilder sb = new StringBuilder();
Index: trunk/src/org/openstreetmap/josm/gui/preferences/imagery/CacheContentsPanel.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/preferences/imagery/CacheContentsPanel.java	(revision 10016)
+++ trunk/src/org/openstreetmap/josm/gui/preferences/imagery/CacheContentsPanel.java	(revision 10021)
@@ -71,4 +71,8 @@
         private Object editorValue;
 
+        private ButtonColumn() {
+            this(null);
+        }
+
         private ButtonColumn(Action action) {
             this.action = action;