Index: trunk/src/org/openstreetmap/josm/gui/MainApplication.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/MainApplication.java	(revision 11253)
+++ trunk/src/org/openstreetmap/josm/gui/MainApplication.java	(revision 11255)
@@ -33,4 +33,6 @@
 import java.util.TreeSet;
 import java.util.logging.Level;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 import javax.swing.JOptionPane;
@@ -152,11 +154,13 @@
                 "\t--offline=<osm_api|josm_website|all>      "+tr("Disable access to the given resource(s), separated by comma")+"\n\n"+
                 tr("options provided as Java system properties")+":\n"+
-                // CHECKSTYLE.OFF: SingleSpaceSeparator
-                "\t-Djosm.pref="    +tr("/PATH/TO/JOSM/PREF    ")+tr("Set the preferences directory")+"\n\n"+
-                "\t-Djosm.userdata="+tr("/PATH/TO/JOSM/USERDATA")+tr("Set the user data directory")+"\n\n"+
-                "\t-Djosm.cache="   +tr("/PATH/TO/JOSM/CACHE   ")+tr("Set the cache directory")+"\n\n"+
-                "\t-Djosm.home="    +tr("/PATH/TO/JOSM/HOMEDIR ")+
-                // CHECKSTYLE.ON: SingleSpaceSeparator
-                tr("Relocate all 3 directories to homedir. Cache directory will be in homedir/cache")+"\n\n"+
+                align("\t-Djosm.dir.name=JOSM") + tr("Change the JOSM directory name") + "\n\n" +
+                align("\t-Djosm.pref=" + tr("/PATH/TO/JOSM/PREF    ")) + tr("Set the preferences directory") + "\n" +
+                align("\t") + tr("Default: {0}", platform.getDefaultPrefDirectory()) + "\n\n" +
+                align("\t-Djosm.userdata=" + tr("/PATH/TO/JOSM/USERDATA")) + tr("Set the user data directory") + "\n" +
+                align("\t") + tr("Default: {0}", platform.getDefaultUserDataDirectory()) + "\n\n" +
+                align("\t-Djosm.cache=" + tr("/PATH/TO/JOSM/CACHE   ")) + tr("Set the cache directory") + "\n" +
+                align("\t") + tr("Default: {0}", platform.getDefaultCacheDirectory()) + "\n\n" +
+                align("\t-Djosm.home=" + tr("/PATH/TO/JOSM/HOMEDIR ")) +
+                tr("Set the preferences+data+cache directory (cache directory will be josm.home/cache)")+"\n\n"+
                 tr("-Djosm.home has lower precedence, i.e. the specific setting overrides the general one")+"\n\n"+
                 tr("note: For some tasks, JOSM needs a lot of memory. It can be necessary to add the following\n" +
@@ -169,8 +173,13 @@
                 "\tjava -jar josm.jar 43.2,11.1,43.4,11.4\n"+
                 "\tjava -Djosm.pref=$XDG_CONFIG_HOME -Djosm.userdata=$XDG_DATA_HOME -Djosm.cache=$XDG_CACHE_HOME -jar josm.jar\n"+
+                "\tjava -Djosm.dir.name=josm_dev -jar josm.jar\n"+
                 "\tjava -Djosm.home=/home/user/.josm_dev -jar josm.jar\n"+
                 "\tjava -Xmx1024m -jar josm.jar\n\n"+
                 tr("Parameters --download, --downloadgps, and --selection are processed in this order.")+'\n'+
                 tr("Make sure you load some data if you use --selection.")+'\n';
+    }
+
+    private static String align(String str) {
+        return str + Stream.generate(() -> " ").limit(Math.max(0, 43 - str.length())).collect(Collectors.joining(""));
     }