Index: trunk/src/org/openstreetmap/josm/gui/dialogs/SearchDialog.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/dialogs/SearchDialog.java	(revision 15108)
+++ trunk/src/org/openstreetmap/josm/gui/dialogs/SearchDialog.java	(revision 15109)
@@ -10,4 +10,6 @@
 import java.awt.GridBagLayout;
 import java.awt.event.ActionEvent;
+import java.awt.event.ItemEvent;
+import java.awt.event.ItemListener;
 import java.awt.event.MouseAdapter;
 import java.awt.event.MouseEvent;
@@ -116,4 +118,5 @@
         regexSearch = new JRadioButton(tr("regular expression"), searchSettings.regexSearch);
         mapCSSSearch = new JRadioButton(tr("MapCSS selector"), searchSettings.mapCSSSearch);
+
         ButtonGroup bg2 = new ButtonGroup();
         bg2.add(standardSearch);
@@ -163,5 +166,5 @@
          * the text field is colored red.
          */
-        document.addDocumentListener(new AbstractTextComponentValidator(editorComponent) {
+        AbstractTextComponentValidator validator = new AbstractTextComponentValidator(editorComponent) {
 
             @Override
@@ -188,5 +191,14 @@
                 }
             }
-        });
+        };
+        document.addDocumentListener(validator);
+        ItemListener validateActionListener = e -> {
+            if (e.getStateChange() == ItemEvent.SELECTED) {
+                validator.validate();
+            }
+        };
+        standardSearch.addItemListener(validateActionListener);
+        regexSearch.addItemListener(validateActionListener);
+        mapCSSSearch.addItemListener(validateActionListener);
 
         /*