diff -urN original/src/gwt/build.xml prefs/src/gwt/build.xml
--- original/src/gwt/build.xml	2011-09-20 08:15:44.000000000 -0700
+++ prefs/src/gwt/build.xml	2011-09-24 00:44:50.386869251 -0700
@@ -101,7 +101,7 @@
             <path refid="project.class.path"/>
          </classpath>
          <!-- add jvmarg -Xss16M or similar if you see a StackOverflowError -->
-         <jvmarg value="-Xmx512M"/>
+         <jvmarg value="-Xmx512M"/> <jvmarg value="-Djava.util.prefs.userRoot=/var/tmp/portage/sci-mathematics/rstudio-0.94.106/homedir"/>
          <arg value="-war"/>
          <arg value="www"/>
          <arg value="-localWorkers"/>
@@ -145,7 +145,7 @@
             <pathelement location="src"/>
             <path refid="project.class.path"/>
          </classpath>
-         <jvmarg value="-Xmx512M"/>
+         <jvmarg value="-Xmx512M"/> <jvmarg value="-Djava.util.prefs.userRoot=/var/tmp/portage/sci-mathematics/rstudio-0.94.106/homedir"/>
          <arg value="-war"/>
          <arg value="www"/>
          <arg value="-noserver"/>