diff --git a/xulrunner/stub/nsXULStub.cpp b/xulrunner/stub/nsXULStub.cpp
--- a/xulrunner/stub/nsXULStub.cpp
+++ b/xulrunner/stub/nsXULStub.cpp
@@ -33,16 +33,17 @@
  * the provisions above, a recipient may use your version of this file under
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * ***** END LICENSE BLOCK ***** */

 #include "nsXPCOMGlue.h"
 #include "nsINIParser.h"
 #include "prtypes.h"
+//#include "plstr.h"
 #include "nsXPCOMPrivate.h" // for XP MAXPATHLEN
 #include "nsMemory.h" // for NS_ARRAY_LENGTH
 #include "nsXULAppAPI.h"
 #include "nsILocalFile.h"

 #include <stdarg.h>

 #ifdef XP_WIN
@@ -107,16 +108,37 @@ static void Output(PRBool isError, const
 		      sizeof(wide_msg) / sizeof(wchar_t));

   MessageBoxW(NULL, wide_msg, L"XULRunner", flags);
 #else
   vfprintf(stderr, fmt, ap);
 #endif

   va_end(ap);
+}
+
+/**
+ * Return true if |arg| matches the given argument name.
+ */
+static PRBool IsArg(const char* arg, const char* s)
+{
+  if (*arg == '-')
+  {
+    if (*++arg == '-')
+      ++arg;
+    //return !PL_strcasecmp(arg, s);
+    return !strcasecmp(arg, s);
+  }
+
+#if defined(XP_WIN) || defined(XP_OS2)
+  if (*arg == '/')
+    return !PL_strcasecmp(++arg, s);
+#endif
+
+  return PR_FALSE;
 }

 class AutoAppData
 {
 public:
   AutoAppData(nsILocalFile* aINIFile) : mAppData(nsnull) {
     nsresult rv = XRE_CreateAppData(aINIFile, &mAppData);
     if (NS_FAILED(rv))
@@ -216,69 +238,114 @@ main(int argc, char **argv)
   // instead of using the MOZILLA_FIVE_HOME hack, which doesn't scale to
   // multiple applications, we will try a series of techniques:
   //
   // 1) use realpath() on argv[0], which works unless we're loaded from the
   //    PATH
   // 2) manually walk through the PATH and look for ourself
   // 3) give up

+  const char *appDataFile = getenv("XUL_APP_FILE");
+  char appDataFileStrDUP[MAXPATHLEN];
+
+  if (!(appDataFile && *appDataFile)) {
+    if (argc < 2) {
+      //Usage(argv[0]);
+      return 1;
+    }
+
+    if (IsArg(argv[1], "app")) {
+      if (argc == 2) {
+        //Usage(argv[0]);
+        return 1;
+      }
+      argv[1] = argv[0];
+      ++argv;
+      --argc;
+    }
+
+    appDataFile = argv[1];
+    argv[1] = argv[0];
+    ++argv;
+    --argc;
+
+    static char kAppEnv[MAXPATHLEN];
+    //PR_snprintf(kAppEnv, MAXPATHLEN, "XUL_APP_FILE=%s", appDataFile);
+    //PR_SetEnv(kAppEnv);
+    snprintf(kAppEnv, MAXPATHLEN, "%s", appDataFile);
+    setenv("XUL_APP_FILE", kAppEnv, 1);
+    printf("main - appDataFile = %s\n", appDataFile);
+  } else {
   struct stat fileStat;
-
   if (!realpath(argv[0], iniPath) || stat(iniPath, &fileStat)) {
     const char *path = getenv("PATH");
     if (!path)
       return 1;

     char *pathdup = strdup(path);
     if (!pathdup)
       return 1;

     PRBool found = PR_FALSE;
     char *token = strtok(pathdup, ":");
     while (token) {
       sprintf(tmpPath, "%s/%s", token, argv[0]);
+      printf("main - tmpPath = %s\n", tmpPath);
       if (realpath(tmpPath, iniPath) && stat(iniPath, &fileStat) == 0) {
         found = PR_TRUE;
         break;
       }
       token = strtok(NULL, ":");
     }
     free (pathdup);
     if (!found)
       return 1;
   }
 #endif

+  printf("main - argv[0] = %s\n", argv[0]);
+  printf("main - iniPath = %s\n", iniPath);
+
   lastSlash = strrchr(iniPath, PATH_SEPARATOR_CHAR);
   if (!lastSlash)
     return 1;
-
+  printf("main - lastSlash = %s\n", lastSlash);
   *(++lastSlash) = '\0';

   // On Linux/Win, look for XULRunner in appdir/xulrunner

   snprintf(greDir, sizeof(greDir),
            "%sxulrunner" XPCOM_FILE_PATH_SEPARATOR XPCOM_DLL,
            iniPath);
+
+  printf("main - greDir2 = %s\n", greDir);

 #ifdef WINCE
   wchar_t wideGreDir[MAX_PATH];
   MultiByteToWideChar(CP_ACP, 0, greDir, -1, wideGreDir, MAX_PATH);
   DWORD fileAttrs = GetFileAttributesW(wideGreDir);
   greFound = fileAttrs != INVALID_FILE_ATTRIBUTES;
 #else
   greFound = (access(greDir, R_OK) == 0);
 #endif
+
   strncpy(lastSlash, "application.ini", sizeof(iniPath) - (lastSlash - iniPath));
+  printf("main - lastSlash2 = %s\n", lastSlash);
+  }

 #endif

+  if (!realpath(appDataFile, appDataFileStrDUP))
+    return 1;
+
+  printf("main - appDataFileStrDUP = %s\n", appDataFileStrDUP);
+
   nsINIParser parser;
-  rv = parser.Init(iniPath);
+//   rv = parser.Init(iniPath);
+  rv = parser.Init(appDataFile);
   if (NS_FAILED(rv)) {
     fprintf(stderr, "Could not read application.ini\n");
     return 1;
   }

   if (!greFound) {
     char minVersion[VERSION_MAXLEN];

@@ -352,17 +419,17 @@ main(int argc, char **argv)
   }

   NS_LogInit();

   int retval;

   { // Scope COMPtr and AutoAppData
     nsCOMPtr<nsILocalFile> iniFile;
-    rv = NS_NewNativeLocalFile(nsDependentCString(iniPath), PR_FALSE,
+    rv = NS_NewNativeLocalFile(nsDependentCString(appDataFileStrDUP), PR_FALSE,
                                getter_AddRefs(iniFile));
     if (NS_FAILED(rv)) {
       Output(PR_TRUE, "Couldn't find application.ini file.\n");
       return 1;
     }

     AutoAppData appData(iniFile);
     if (!appData) {