diff --git a/direct/src/p3d/AppRunner.py b/direct/src/p3d/AppRunner.py
index 6cabdfa4e5..5ede54c820 100644
--- a/direct/src/p3d/AppRunner.py
+++ b/direct/src/p3d/AppRunner.py
@@ -342,10 +342,11 @@ class AppRunner(DirectObject):
 
         # Now set up Python to import this stuff.
         VFSImporter.register()
-        sys.path = [ self.multifileRoot ] + sys.path
+        sys.path.append(self.multifileRoot)
+        print "sys.path is: %s" % (sys.path)
 
         # Put our root directory on the model-path, too.
-        getModelPath().prependDirectory(self.multifileRoot)
+        getModelPath().appendDirectory(self.multifileRoot)
 
         # Replace the builtin open and file symbols so user code will get
         # our versions by default, which can open and read files out of
diff --git a/direct/src/p3d/FileSpec.py b/direct/src/p3d/FileSpec.py
index 65142d871a..30cf82087f 100644
--- a/direct/src/p3d/FileSpec.py
+++ b/direct/src/p3d/FileSpec.py
@@ -119,7 +119,9 @@ class FileSpec:
         # The hash is OK after all.  Change the file's timestamp back
         # to what we expect it to be, so we can quick-verify it
         # successfully next time.
+        os.chmod(pathname.toOsSpecific(), 0644)
         os.utime(pathname.toOsSpecific(), (st.st_atime, self.timestamp))
+        os.chmod(pathname.toOsSpecific(), 0444)
 
         return True
         
diff --git a/direct/src/p3d/PackageInfo.py b/direct/src/p3d/PackageInfo.py
index b61e2e4ab9..a1d035b691 100644
--- a/direct/src/p3d/PackageInfo.py
+++ b/direct/src/p3d/PackageInfo.py
@@ -621,12 +621,12 @@ class PackageInfo:
 
         if not foundOnPath:
             # Not already here; add it.
-            sys.path.insert(0, root)
+            sys.path.append(root)
 
         # Put it on the model-path, too.  We do this indiscriminantly,
         # because the Panda3D runtime won't be adding things to the
         # model-path, so it shouldn't be already there.
-        getModelPath().prependDirectory(self.packageDir)
+        getModelPath().appendDirectory(self.packageDir)
 
         # Set the environment variable to reference the package root.
         envvar = '%s_ROOT' % (self.packageName.upper())
diff --git a/direct/src/p3d/Packager.py b/direct/src/p3d/Packager.py
index c740cd46cb..205950336d 100644
--- a/direct/src/p3d/Packager.py
+++ b/direct/src/p3d/Packager.py
@@ -1480,6 +1480,8 @@ class Packager:
         # hosted.
         self.host = PandaSystem.getPackageHostUrl()
         self.hostDescriptiveName = None
+        self.hostMirrors = []
+        self.altHosts = {}
 
         # A search list for previously-built local packages.
         self.installSearch = ConfigVariableSearchPath('pdef-path')
@@ -1641,6 +1643,21 @@ class Packager:
         # file.
         self.contents = {}
 
+    def setHost(self, host, descriptiveName = None, mirrors = []):
+        """ Specifies the URL that will ultimately host these
+        contents. """
+        
+        self.host = host
+        self.hostDescriptiveName = descriptiveName
+        self.hostMirrors = mirrors
+
+    def addAltHost(self, keyword, host, descriptiveName = None, mirrors = []):
+        """ Adds an alternate host from which an alternate version of
+        these contents may be downloaded, if specified on the HTML
+        page. """
+
+        self.altHosts[keyword] = (host, descriptiveName, mirrors)
+
     def addWindowsSearchPath(self, searchPath, varname):
         """ Expands $varname, interpreting as a Windows-style search
         path, and adds its contents to the indicated DSearchPath. """
@@ -2587,8 +2604,12 @@ class Packager:
         doc.InsertEndChild(decl)
 
         xcontents = TiXmlElement('contents')
-        if self.hostDescriptiveName:
-            xcontents.SetAttribute('descriptive_name', self.hostDescriptiveName)
+
+        xhost = self.makeHostXml('host', self.host, self.hostDescriptiveName, self.hostMirrors)
+        xcontents.InsertEndChild(xhost)
+        for keyword, (host, descriptiveName, mirrors) in self.altHosts.items():
+            xhost = self.makeHostXml('alt_host', host, descriptiveName, mirrors)
+            xcontents.InsertEndChild(xhost)
 
         contents = self.contents.items()
         contents.sort()
@@ -2598,6 +2619,22 @@ class Packager:
 
         doc.InsertEndChild(xcontents)
         doc.SaveFile()
+
+    def makeHostXml(self, element, host, descriptiveName, mirrors):
+        """ Constructs the <host> or <alt_host> entry for the
+        indicated host and its mirrors. """
+
+        xhost = TiXmlElement(element)
+        xhost.SetAttribute('url', host)
+        if descriptiveName:
+            xhost.SetAttribute('descriptive_name', descriptiveName)
+
+        for mirror in mirrors:
+            xmirror = TiXmlElement('mirror')
+            xmirror.SetAttribute('url', mirror)
+            xhost.InsertEndChild(xmirror)
+
+        return xhost
         
 
 # The following class and function definitions represent a few sneaky
diff --git a/direct/src/p3d/packp3d.py b/direct/src/p3d/packp3d.py
index 56078107f7..481f990d57 100755
--- a/direct/src/p3d/packp3d.py
+++ b/direct/src/p3d/packp3d.py
@@ -143,6 +143,7 @@ def makePackedApp(args):
     
     packager.installDir = appDir
     getModelPath().appendDirectory(root)
+    packager.allowPythonDev = allowPythonDev
 
     try:
         packager.setup()
@@ -156,8 +157,6 @@ def makePackedApp(args):
 
         if autoStart:
             packager.do_config(auto_start = True)
-        if allowPythonDev:
-            packager.do_config(allow_python_dev = True)
 
         packager.do_dir(root)
         packager.do_mainModule(mainModule)
diff --git a/direct/src/p3d/panda3d.pdef b/direct/src/p3d/panda3d.pdef
index 88d36e0c52..d1d7c53145 100755
--- a/direct/src/p3d/panda3d.pdef
+++ b/direct/src/p3d/panda3d.pdef
@@ -202,7 +202,8 @@ class packp3d(p3d):
     # the targeted runtime.
 
     config(display_name = "Panda3D Application Packer",
-           hidden = True, platform_specific = False)
+           hidden = True, platform_specific = False,
+           keep_user_env = True)
     require('panda3d', 'egg')
 
     mainModule('direct.p3d.packp3d')
@@ -214,7 +215,8 @@ class ppackage(p3d):
     # more packages or p3d applications.
 
     config(display_name = "Panda3D General Package Utility",
-           hidden = True, platform_specific = False)
+           hidden = True, platform_specific = False,
+           keep_user_env = True)
     require('panda3d', 'egg')
 
     mainModule('direct.p3d.ppackage')
diff --git a/direct/src/plugin/mkdir_complete.cxx b/direct/src/plugin/mkdir_complete.cxx
index 65eaa3ecd5..44d4a54e26 100755
--- a/direct/src/plugin/mkdir_complete.cxx
+++ b/direct/src/plugin/mkdir_complete.cxx
@@ -17,6 +17,7 @@
 
 #ifdef _WIN32
 #include <windows.h>
+#include <io.h>    // chmod()
 #else
 #include <fcntl.h>
 #include <sys/stat.h>  // for mkdir()
@@ -125,6 +126,10 @@ mkdir_complete(const string &dirname, ostream &logfile) {
 bool
 mkfile_complete(const string &filename, ostream &logfile) {
   // Make sure we delete any previously-existing file first.
+#ifdef _WIN32
+  // Windows can't delete a file if it's read-only.  Weird.
+  chmod(filename.c_str(), 0644);
+#endif
   unlink(filename.c_str());
 
 #ifdef _WIN32
diff --git a/direct/src/plugin/p3dInstance.cxx b/direct/src/plugin/p3dInstance.cxx
index 64ac465186..160eaea268 100644
--- a/direct/src/plugin/p3dInstance.cxx
+++ b/direct/src/plugin/p3dInstance.cxx
@@ -312,10 +312,13 @@ set_p3d_filename(const string &p3d_filename) {
 ////////////////////////////////////////////////////////////////////
 void P3DInstance::
 set_wparams(const P3DWindowParams &wparams) {
-  nout << "set_wparams\n";
   _got_wparams = true;
   _wparams = wparams;
 
+  nout << "set_wparams: " << wparams.get_window_type()
+       << " " << wparams.get_win_width() << " " << wparams.get_win_height()
+       << "\n";
+
   if (_hidden || _wparams.get_win_width() == 0 || _wparams.get_win_height() == 0) {
     // If we're a hidden app, or if the window has no size, then it is
     // really a hidden window, regardless of what type it claims to
@@ -1211,6 +1214,11 @@ scan_app_desc_file(TiXmlDocument *doc) {
       _allow_python_dev = (allow_python_dev != 0);
     }
 
+    int keep_user_env = 0;
+    if (xconfig->QueryIntAttribute("keep_user_env", &keep_user_env) == TIXML_SUCCESS) {
+      _keep_user_env = (keep_user_env != 0);
+    }
+
     int auto_start = 0;
     if (xconfig->QueryIntAttribute("auto_start", &auto_start) == TIXML_SUCCESS) {
       _auto_start = (auto_start != 0);
diff --git a/direct/src/plugin/p3dInstance.h b/direct/src/plugin/p3dInstance.h
index 9c30f3bbe3..ddec17a44f 100644
--- a/direct/src/plugin/p3dInstance.h
+++ b/direct/src/plugin/p3dInstance.h
@@ -223,6 +223,7 @@ private:
   string _log_basename;
   bool _hidden;
   bool _allow_python_dev;
+  bool _keep_user_env;
   bool _auto_start;
   bool _auth_button_approved;
 
diff --git a/direct/src/plugin/p3dPackage.cxx b/direct/src/plugin/p3dPackage.cxx
index c7736ecdfe..7693bcf027 100755
--- a/direct/src/plugin/p3dPackage.cxx
+++ b/direct/src/plugin/p3dPackage.cxx
@@ -24,6 +24,10 @@
 #include <algorithm>
 #include <fstream>
 
+#ifdef _WIN32
+#include <io.h>    // chmod()
+#endif
+
 // The relative breakdown of the full install process.  Each phase is
 // worth this fraction of the total movement of the progress bar.
 static const double download_portion = 0.9;
@@ -365,10 +369,8 @@ desc_file_download_finished(bool success) {
     return;
   }
 
-#ifndef _WIN32
   // Now that we've downloaded the desc file, make it read-only.
   chmod(_desc_file_pathname.c_str(), 0444);
-#endif
 
   if (_package_solo) {
     // No need to load it: the desc file *is* the package.
@@ -459,6 +461,11 @@ got_desc_file(TiXmlDocument *doc, bool freshly_downloaded) {
     string filename = (*ci);
     nout << "Removing " << filename << "\n";
     string pathname = _package_dir + "/" + filename;
+
+#ifdef _WIN32
+    // Windows can't delete a file if it's read-only.
+    chmod(pathname.c_str(), 0644);
+#endif
     unlink(pathname.c_str());
   }
 
@@ -723,12 +730,13 @@ uncompress_archive() {
     return;
   }
 
-#ifndef _WIN32
   // Now that we've verified the archive, make it read-only.
   chmod(target_pathname.c_str(), 0444);
-#endif
 
   // Now we can safely remove the compressed archive.
+#ifdef _WIN32
+  chmod(source_pathname.c_str(), 0644);
+#endif
   unlink(source_pathname.c_str());
 
   // All done uncompressing.
@@ -844,9 +852,16 @@ start_download(P3DPackage::DownloadType dtype, const string &url,
   assert(_active_download == NULL);
   
   if (!allow_partial) {
+#ifdef _WIN32
+    // Windows can't delete a file if it's read-only.
+    chmod(pathname.c_str(), 0644);
+#endif
     unlink(pathname.c_str());
+  } else {
+    // Make sure the file is writable.
+    chmod(pathname.c_str(), 0644);
   }
-
+    
   Download *download = new Download(this, dtype);
   download->set_url(url);
   download->set_filename(pathname);
diff --git a/direct/src/plugin/p3dSession.cxx b/direct/src/plugin/p3dSession.cxx
index 27f1ca1b6d..6e73c5a8e4 100644
--- a/direct/src/plugin/p3dSession.cxx
+++ b/direct/src/plugin/p3dSession.cxx
@@ -662,11 +662,13 @@ start_p3dpython(P3DInstance *inst) {
 
   _python_root_dir = inst->_panda3d->get_package_dir();
 
-  // Change the current directory to the standard start directory, but
-  // only if the runtime environment told us the original current
-  // directory isn't meaningful.
-  _use_start_dir = !inst_mgr->get_trusted_environment();
-  if (_use_start_dir) {
+  // If we're not to be preserving the user's current directory, then
+  // we'll need to change to the standard start directory.
+  _keep_user_env = false;
+  if (inst_mgr->get_trusted_environment() && inst->_keep_user_env) {
+    _keep_user_env = true;
+  }
+  if (!_keep_user_env) {
     mkdir_complete(_start_dir, nout);
   }
 
@@ -759,13 +761,17 @@ start_p3dpython(P3DInstance *inst) {
   // Populate the new process' environment.
   _env = string();
 
-  if (!inst_mgr->get_trusted_environment()) {
+  if (!_keep_user_env) {
+    // Reconstruct an environment just for running the process.
+    // Completely replace most of the existing environment variables
+    // with our own.
+
     // These are the enviroment variables we forward from the current
     // environment, if they are set.
     const char *keep[] = {
       "TMP", "TEMP", "HOME", "USER", 
 #ifdef _WIN32
-      "SYSTEMROOT", "USERPROFILE", "COMSPEC", "PANDA_ROOT",
+      "SYSTEMROOT", "USERPROFILE", "COMSPEC",
 #endif
 #ifdef HAVE_X11
       "DISPLAY",
@@ -783,8 +789,9 @@ start_p3dpython(P3DInstance *inst) {
     }
 
   } else {
-    // In a trusted environment, we forward *all* environment
-    // variables, except those defined specifically below.
+    // In a trusted environment, when the application asks us to, we
+    // forward *all* environment variables, except those defined
+    // specifically below.
     const char *dont_keep[] = {
       "PATH", "LD_LIBRARY_PATH", "DYLD_LIBRARY_PATH",
       "PYTHONPATH", "PYTHONHOME", "PRC_PATH", "PANDA_PRC_PATH",
@@ -1214,10 +1221,10 @@ win_create_process() {
   startup_info.wShowWindow = SW_HIDE;
   startup_info.dwFlags |= STARTF_USESHOWWINDOW;
 
-  // If _use_start_dir is false, meaning not to change the current
-  // directory, then pass NULL in to CreateProcess().
+  // If _keep_user_env, meaning not to change the current directory,
+  // then pass NULL in to CreateProcess().
   const char *start_dir_cstr = NULL;
-  if (_use_start_dir) {
+  if (!_keep_user_env) {
     start_dir_cstr = _start_dir.c_str();
   }
 
diff --git a/direct/src/plugin/p3dSession.h b/direct/src/plugin/p3dSession.h
index d09631a689..0433150ce6 100644
--- a/direct/src/plugin/p3dSession.h
+++ b/direct/src/plugin/p3dSession.h
@@ -90,7 +90,7 @@ private:
   string _log_pathname;
   string _python_root_dir;
   string _start_dir;
-  bool _use_start_dir;
+  bool _keep_user_env;
 
   // This information is passed to create_process(), or to
   // p3dpython_thread_run().