Index: trunk/src/org/openstreetmap/josm/actions/DiskAccessAction.java
===================================================================
--- trunk/src/org/openstreetmap/josm/actions/DiskAccessAction.java	(revision 1977)
+++ trunk/src/org/openstreetmap/josm/actions/DiskAccessAction.java	(revision 1978)
@@ -5,9 +5,12 @@
 
 import java.io.File;
+
 import javax.swing.JFileChooser;
+import javax.swing.filechooser.FileFilter;
+
 import org.openstreetmap.josm.Main;
 import org.openstreetmap.josm.gui.ExtendedDialog;
+import org.openstreetmap.josm.io.FileImporter;
 import org.openstreetmap.josm.tools.Shortcut;
-import org.openstreetmap.josm.io.FileImporter;
 
 /**
@@ -31,9 +34,18 @@
 
         fc.setMultiSelectionEnabled(multiple);
+        fc.setAcceptAllFileFilterUsed(false);
+        FileFilter defaultFilter = null;
         for (FileImporter imExporter: ExtensionFileFilter.importers) {
             fc.addChoosableFileFilter(imExporter.filter);
+            if (imExporter.filter.defaultExtension.endsWith("osm")) {
+                defaultFilter = imExporter.filter;
+            }
+
         }
 
-        fc.setAcceptAllFileFilterUsed(true);
+        if (defaultFilter != null) {
+            fc.setFileFilter(defaultFilter);
+        }
+
 
         int answer = open ? fc.showOpenDialog(Main.parent) : fc.showSaveDialog(Main.parent);