Index: trunk/src/org/openstreetmap/josm/Main.java
===================================================================
--- trunk/src/org/openstreetmap/josm/Main.java	(revision 1095)
+++ trunk/src/org/openstreetmap/josm/Main.java	(revision 1096)
@@ -181,5 +181,6 @@
 
 	/**
-	 * Remove the specified layer from the map. If it is the last layer, remove the map as well.
+	 * Remove the specified layer from the map. If it is the last layer, 
+     * remove the map as well.
 	 */
 	public final void removeLayer(final Layer layer) {
@@ -217,6 +218,6 @@
 
 	/**
-	 * Load all plugins specified in preferences. If the parameter is <code>true</code>, all
-	 * early plugins are loaded (before constructor).
+	 * Load all plugins specified in preferences. If the parameter is 
+     * <code>true</code>, all early plugins are loaded (before constructor).
 	 */
 	public static void loadPlugins(boolean early) {
@@ -229,8 +230,6 @@
 
 		String [] oldplugins = new String[] {"mappaint", "unglueplugin", "lang-de","lang-en_GB","lang-fr","lang-it","lang-pl","lang-ro","lang-ru"};
-		for(String p : oldplugins)
-		{
-			if(plugins.contains(p))
-			{
+		for (String p : oldplugins) {
+			if (plugins.contains(p)) {
 				plugins.remove(p);
 				Main.pref.removeFromCollection("plugins", p);
@@ -248,6 +247,5 @@
 				if (info.early != early)
 					continue;
-				if (info.mainversion != null && info.mainversion.compareTo(AboutAction.version) > 0)
-				{
+				if (info.mainversion != null && info.mainversion.compareTo(AboutAction.version) > 0) {
 					JOptionPane.showMessageDialog(Main.parent, tr("Plugin requires JOSM update: {0}.", pluginName));
 					continue;
@@ -264,17 +262,14 @@
 		}
 
-		if(!early)
-		{
+		if (!early) {
 			long tim = System.currentTimeMillis();
 			long last = Main.pref.getLong("pluginmanager.lastupdate", 0);
 			Integer maxTime = Main.pref.getInteger("pluginmanager.warntime", 30);
-			if(last <= 0)
-			{
+			if (last <= 0) {
 				Main.pref.put("pluginmanager.lastupdate",Long.toString(tim));
-			}
-			else if(tim - last >= maxTime*1000*24*60*60)
-			{
-				long d = (tim - last)/(24*60*60*1000);
-				JOptionPane.showMessageDialog(Main.parent, tr("Last plugin update more than {0} days ago.", d));
+			} else if (tim - last >= maxTime*1000l*24*60*60) {
+				long d = (tim - last)/(24*60*60*1000l);
+				JOptionPane.showMessageDialog(Main.parent, 
+                    tr("Last plugin update more than {0} days ago.", d));
 			}
 		}
@@ -348,7 +343,4 @@
 	}
 
-
-
-
 	/**
 	 * Use this to register shortcuts to
@@ -357,7 +349,7 @@
 
 
-	////////////////////////////////////////////////////////////////////////////////////////
+	///////////////////////////////////////////////////////////////////////////
 	//  Implementation part
-	////////////////////////////////////////////////////////////////////////////////////////
+	///////////////////////////////////////////////////////////////////////////
 
 	public static JPanel panel = new JPanel(new BorderLayout());
Index: trunk/src/org/openstreetmap/josm/gui/preferences/PluginPreference.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/preferences/PluginPreference.java	(revision 1095)
+++ trunk/src/org/openstreetmap/josm/gui/preferences/PluginPreference.java	(revision 1096)
@@ -12,4 +12,5 @@
 import java.io.File;
 import java.io.FileReader;
+import java.io.IOException;
 import java.util.Arrays;
 import java.util.Collection;
@@ -113,13 +114,13 @@
 		JButton morePlugins = new JButton(tr("Download List"));
 		morePlugins.addActionListener(new ActionListener(){
-			public void actionPerformed(ActionEvent e) {
-				int count = PluginDownloader.downloadDescription();
-				if (count > 0)
-					JOptionPane.showMessageDialog(Main.parent,
-							trn("Downloaded plugin information from {0} site",
-									"Downloaded plugin information from {0} sites", count, count));
-				else
-					JOptionPane.showMessageDialog(Main.parent, tr("No plugin information found."));
-				refreshPluginPanel(gui);
+		    public void actionPerformed(ActionEvent e) {
+		        int count = PluginDownloader.downloadDescription();
+		        if (count > 0)
+		            JOptionPane.showMessageDialog(Main.parent,
+		                trn("Downloaded plugin information from {0} site",
+		                    "Downloaded plugin information from {0} sites", count, count));
+		        else
+		            JOptionPane.showMessageDialog(Main.parent, tr("No plugin information found."));
+		        refreshPluginPanel(gui);
 			}
 		});
@@ -132,5 +133,4 @@
 				refreshPluginPanel(gui);
 			}
-
 		});
 		plugin.add(update, GBC.std().insets(0,0,10,0));
@@ -141,5 +141,4 @@
 				configureSites();
 			}
-
 		});
 		plugin.add(configureSites, GBC.std());
@@ -286,4 +285,23 @@
 			pluginCheck.addActionListener(new ActionListener(){
 				public void actionPerformed(ActionEvent e) {
+                    // if user enabled a plugin, it is not loaded but found somewhere on disk: offer to delete jar
+                    if (pluginCheck.isSelected()) {
+                        PluginInformation plinfo = PluginInformation.findPlugin(plugin.name);
+                        if ((PluginInformation.getLoaded(plugin.name) == null) && (plinfo != null)) {
+                            try {
+                                int answer = JOptionPane.showConfirmDialog(Main.parent, 
+                                    tr("Plugin archive already available. Do you want to download current version by deleting existing archive?\n\n{0}",
+                                    plinfo.file.getCanonicalPath()), tr("Plugin already exists"), JOptionPane.OK_CANCEL_OPTION);
+                                if (answer == JOptionPane.OK_OPTION) {
+                                    if (!plinfo.file.delete()) {
+                                        JOptionPane.showMessageDialog(Main.parent, tr("Error deleting plugin file: {0}", plinfo.file.getCanonicalPath()));
+                                    }
+                                }
+                            } catch (IOException e1) {
+                                e1.printStackTrace();
+                                JOptionPane.showMessageDialog(Main.parent, tr("Error deleting plugin file: {0}", e1.getMessage()));
+                            }
+                        }
+                    }
 					pluginMap.put(plugin, pluginCheck.isSelected());
 				}