Index: applications/editors/josm/plugins/opendata/src/org/openstreetmap/josm/plugins/opendata/core/gui/ModulePreference.java
===================================================================
--- applications/editors/josm/plugins/opendata/src/org/openstreetmap/josm/plugins/opendata/core/gui/ModulePreference.java	(revision 28008)
+++ applications/editors/josm/plugins/opendata/src/org/openstreetmap/josm/plugins/opendata/core/gui/ModulePreference.java	(revision 28010)
@@ -209,7 +209,7 @@
      * @return the list of modules waiting for update or download
      */
-    /*public List<ModuleInformation> getModulesScheduledForUpdateOrDownload() {
+    public List<ModuleInformation> getModulesScheduledForUpdateOrDownload() {
         return model != null ? model.getModulesScheduledForUpdateOrDownload() : null;
-    }*/
+    }
 
     public boolean ok() {
Index: applications/editors/josm/plugins/opendata/src/org/openstreetmap/josm/plugins/opendata/core/gui/ModulePreferencesModel.java
===================================================================
--- applications/editors/josm/plugins/opendata/src/org/openstreetmap/josm/plugins/opendata/core/gui/ModulePreferencesModel.java	(revision 28008)
+++ applications/editors/josm/plugins/opendata/src/org/openstreetmap/josm/plugins/opendata/core/gui/ModulePreferencesModel.java	(revision 28010)
@@ -190,5 +190,5 @@
      * @return the list of modules waiting for update or download
      */
-    /*public List<ModuleInformation> getModulesScheduledForUpdateOrDownload() {
+    public List<ModuleInformation> getModulesScheduledForUpdateOrDownload() {
         List<ModuleInformation> ret = new ArrayList<ModuleInformation>();
         for (String module: pendingDownloads) {
@@ -200,5 +200,5 @@
         }
         return ret;
-    }*/
+    }
 
     /**
Index: applications/editors/josm/plugins/opendata/src/org/openstreetmap/josm/plugins/opendata/core/gui/OdPreferenceSetting.java
===================================================================
--- applications/editors/josm/plugins/opendata/src/org/openstreetmap/josm/plugins/opendata/core/gui/OdPreferenceSetting.java	(revision 28008)
+++ applications/editors/josm/plugins/opendata/src/org/openstreetmap/josm/plugins/opendata/core/gui/OdPreferenceSetting.java	(revision 28010)
@@ -27,4 +27,5 @@
 import javax.swing.JCheckBox;
 import javax.swing.JLabel;
+import javax.swing.JOptionPane;
 import javax.swing.JPanel;
 import javax.swing.JScrollPane;
@@ -33,4 +34,5 @@
 import javax.swing.JTextField;
 import javax.swing.SwingConstants;
+import javax.swing.SwingUtilities;
 
 import org.openstreetmap.josm.Main;
@@ -38,4 +40,6 @@
 import org.openstreetmap.josm.gui.preferences.PreferenceTabbedPane;
 import org.openstreetmap.josm.plugins.opendata.core.OdConstants;
+import org.openstreetmap.josm.plugins.opendata.core.modules.ModuleDownloadTask;
+import org.openstreetmap.josm.plugins.opendata.core.modules.ModuleInformation;
 import org.openstreetmap.josm.tools.GBC;
 
@@ -142,10 +146,80 @@
     @Override
     public boolean ok() {
-    	modulePref.ok();
+    	boolean result = modulePref.ok();
    		//Main.pref.put(PREF_COORDINATES, rbWGS84.isSelected() ? VALUE_WGS84 : VALUE_CC9ZONES);
    		Main.pref.put(PREF_OAPI, oapi.getText());
    		Main.pref.put(PREF_XAPI, xapi.getText());
    		Main.pref.put(PREF_RAWDATA, rawData.isSelected());
-        return false;
+        
+        // create a task for downloading modules if the user has activated, yet not downloaded,
+        // new modules
+        //
+        final List<ModuleInformation> toDownload = modulePref.getModulesScheduledForUpdateOrDownload();
+        final ModuleDownloadTask task;
+        if (toDownload != null && ! toDownload.isEmpty()) {
+            task = new ModuleDownloadTask(masterPanel, toDownload, tr("Download modules"));
+        } else {
+        	task = null;
+        }
+        
+        // this is the task which will run *after* the modules are downloaded
+        //
+        final Runnable continuation = new Runnable() {
+            public void run() {
+                boolean requiresRestart = false;
+                if (task != null && !task.isCanceled()) {
+                    if (!task.getDownloadedModules().isEmpty()) {
+                        requiresRestart = true;
+                    }
+                }
+
+                // build the messages. We only display one message, including the status
+                // information from the module download task and - if necessary - a hint
+                // to restart JOSM
+                //
+                StringBuilder sb = new StringBuilder();
+                sb.append("<html>");
+                if (task != null && !task.isCanceled()) {
+                    sb.append(ModulePreference.buildDownloadSummary(task));
+                }
+                if (requiresRestart) {
+                    sb.append(tr("You have to restart JOSM for some settings to take effect."));
+                }
+                sb.append("</html>");
+
+                // display the message, if necessary
+                //
+                if ((task != null && !task.isCanceled()) || requiresRestart) {
+                    JOptionPane.showMessageDialog(
+                            Main.parent,
+                            sb.toString(),
+                            tr("Warning"),
+                            JOptionPane.WARNING_MESSAGE
+                            );
+                }
+                Main.parent.repaint();
+            }
+        };
+
+        if (task != null) {
+            // if we have to launch a module download task we do it asynchronously, followed
+            // by the remaining "save preferences" activites run on the Swing EDT.
+            //
+            Main.worker.submit(task);
+            Main.worker.submit(
+                    new Runnable() {
+                        public void run() {
+                            SwingUtilities.invokeLater(continuation);
+                        }
+                    }
+                    );
+        } else {
+            // no need for asynchronous activities. Simply run the remaining "save preference"
+            // activities on this thread (we are already on the Swing EDT
+            //
+            continuation.run();
+        }
+
+        return task == null ? result : false;
     }
 }