Index: trunk/src/org/openstreetmap/josm/gui/dialogs/properties/TagEditHelper.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/dialogs/properties/TagEditHelper.java	(revision 11197)
+++ trunk/src/org/openstreetmap/josm/gui/dialogs/properties/TagEditHelper.java	(revision 11198)
@@ -817,5 +817,5 @@
             while (true) {
                 s = JOptionPane.showInputDialog(this, tr("Please enter the number of recently added tags to display"), s);
-                if (s == null) {
+                if (s == null || s.isEmpty()) {
                     return;
                 }
Index: trunk/src/org/openstreetmap/josm/gui/preferences/plugin/PluginPreference.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/preferences/plugin/PluginPreference.java	(revision 11197)
+++ trunk/src/org/openstreetmap/josm/gui/preferences/plugin/PluginPreference.java	(revision 11198)
@@ -591,5 +591,5 @@
                             JOptionPane.QUESTION_MESSAGE
                             );
-                    if (s != null) {
+                    if (s != null && !s.isEmpty()) {
                         model.addElement(s);
                     }
@@ -617,5 +617,5 @@
                             list.getSelectedValue()
                             );
-                    if (s != null) {
+                    if (s != null && !s.isEmpty()) {
                         model.setElementAt(s, list.getSelectedIndex());
                     }
Index: trunk/src/org/openstreetmap/josm/gui/widgets/EditableList.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/widgets/EditableList.java	(revision 11197)
+++ trunk/src/org/openstreetmap/josm/gui/widgets/EditableList.java	(revision 11198)
@@ -50,5 +50,5 @@
                     title,
                     JOptionPane.QUESTION_MESSAGE);
-            if (source != null) {
+            if (source != null && !source.isEmpty()) {
                 ((DefaultListModel<String>) sourcesList.getModel()).addElement(source);
             }
@@ -65,5 +65,5 @@
                 if (sourcesList.getModel().getSize() == 0) {
                     String source1 = JOptionPane.showInputDialog(Main.parent, title, title, JOptionPane.QUESTION_MESSAGE);
-                    if (source1 != null) {
+                    if (source1 != null && !source1.isEmpty()) {
                         ((DefaultListModel<String>) sourcesList.getModel()).addElement(source1);
                     }
@@ -82,5 +82,5 @@
                         JOptionPane.QUESTION_MESSAGE, null, null,
                         sourcesList.getSelectedValue());
-                if (source2 != null) {
+                if (source2 != null && !source2.isEmpty()) {
                     ((DefaultListModel<String>) sourcesList.getModel()).setElementAt(source2, row);
                 }