diff --git a/dtool/src/dtoolutil/executionEnvironment.I b/dtool/src/dtoolutil/executionEnvironment.I
index 52ea458b67..4a1b4ac697 100644
--- a/dtool/src/dtoolutil/executionEnvironment.I
+++ b/dtool/src/dtoolutil/executionEnvironment.I
@@ -112,3 +112,14 @@ INLINE string ExecutionEnvironment::
 get_binary_name() {
   return get_ptr()->ns_get_binary_name();
 }
+
+////////////////////////////////////////////////////////////////////
+//     Function: ExecutionEnvironment::get_dtool_name
+//       Access: Public, Static
+//  Description: Returns the name of the libdtool DLL that
+//               is used in this program, if it can be determined.
+////////////////////////////////////////////////////////////////////
+INLINE string ExecutionEnvironment::
+get_dtool_name() {
+  return get_ptr()->ns_get_dtool_name();
+}
diff --git a/dtool/src/dtoolutil/executionEnvironment.cxx b/dtool/src/dtoolutil/executionEnvironment.cxx
index 7ac74a4882..23bafe4685 100644
--- a/dtool/src/dtoolutil/executionEnvironment.cxx
+++ b/dtool/src/dtoolutil/executionEnvironment.cxx
@@ -30,7 +30,6 @@
 #include <windows.h>
 #endif
 
-
 // We define the symbol PREREAD_ENVIRONMENT if we cannot rely on
 // getenv() to read environment variables at static init time.  In
 // this case, we must read all of the environment variables directly
@@ -291,6 +290,21 @@ ns_get_binary_name() const {
   return _binary_name;
 }
 
+////////////////////////////////////////////////////////////////////
+//     Function: ExecutionEnvironment::ns_get_dtool_name
+//       Access: Private
+//  Description: Returns the name of the libdtool DLL that
+//               is used in this program, if it can be determined.  The
+//               nonstatic implementation.
+////////////////////////////////////////////////////////////////////
+string ExecutionEnvironment::
+ns_get_dtool_name() const {
+  if (_dtool_name.empty()) {
+    return "unknown";
+  }
+  return _dtool_name;
+}
+
 ////////////////////////////////////////////////////////////////////
 //     Function: ExecutionEnvironment::get_ptr
 //       Access: Private, Static
@@ -365,9 +379,36 @@ read_environment_variables() {
 ////////////////////////////////////////////////////////////////////
 void ExecutionEnvironment::
 read_args() {
-#if defined(HAVE_GLOBAL_ARGV)
-  int argc = GLOBAL_ARGC;
 
+#ifdef WIN32_VC
+  HMODULE dllhandle = GetModuleHandle("libdtool.dll");
+  if (dllhandle != 0) {
+    static const DWORD buffer_size = 1024;
+    char buffer[buffer_size];
+    DWORD size = GetModuleFileName(dllhandle, buffer, buffer_size);
+    if (size != 0) {
+      _dtool_name = Filename::from_os_specific(string(buffer,size));
+    }
+  }
+#endif
+
+#if defined(HAVE_PROC_SELF_MAPS)
+  // This is how you tell whether or not libdtool.so is loaded,
+  // and if so, where it was loaded from.
+  ifstream maps("/proc/self/maps");
+  while (!maps.fail() && !maps.eof()) {
+    char buffer[PATH_MAX];
+    buffer[0] = 0;
+    maps.getline(buffer, PATH_MAX);
+    char *tail = strrchr(buffer,'/');
+    char *head = strchr(buffer,'/');
+    if (tail && head && (strcmp(tail,"/libdtool.so")==0)) {
+      _dtool_name = head;
+    }
+  }
+  maps.close();
+#endif
+  
 #ifdef WIN32_VC
   static const DWORD buffer_size = 1024;
   char buffer[buffer_size];
@@ -377,10 +418,26 @@ read_args() {
   }
 #endif  // WIN32_VC
 
+#if defined(HAVE_PROC_SELF_EXE)
+  // This is more reliable than using (argc,argv), so it given precedence.
+  if (_binary_name.empty()) {
+    char readlinkbuf[PATH_MAX];
+    int pathlen = readlink("/proc/self/exe",readlinkbuf,PATH_MAX-1);
+    if (pathlen > 0) {
+      readlinkbuf[pathlen] = 0;
+      _binary_name = readlinkbuf;
+    }
+  }
+#endif
+
+#if defined(HAVE_GLOBAL_ARGV)
+  int argc = GLOBAL_ARGC;
+
   if (_binary_name.empty() && argc > 0) {
     _binary_name = GLOBAL_ARGV[0];
+    // This really needs to be resolved against PATH.
   }
-
+  
   for (int i = 1; i < argc; i++) {
     _args.push_back(GLOBAL_ARGV[i]);
   }
@@ -397,7 +454,7 @@ read_args() {
     cerr << "Cannot read /proc/self/cmdline; command-line arguments unavailable to config.\n";
     return;
   }
-
+  
   int ch = proc.get();
   int index = 0;
   while (!proc.eof() && !proc.fail()) {
@@ -409,7 +466,8 @@ read_args() {
     }
 
     if (index == 0) {
-      _binary_name = arg;
+      if (_binary_name.empty())
+	_binary_name = arg;
     } else {
       _args.push_back(arg);
     }
@@ -420,4 +478,7 @@ read_args() {
 #else
   cerr << "Warning: command line parameters unavailable to dconfig.\n";
 #endif
+
+  if (_dtool_name.empty())
+    _dtool_name = _binary_name;
 }
diff --git a/dtool/src/dtoolutil/executionEnvironment.h b/dtool/src/dtoolutil/executionEnvironment.h
index 33cc896bb3..884762f929 100644
--- a/dtool/src/dtoolutil/executionEnvironment.h
+++ b/dtool/src/dtoolutil/executionEnvironment.h
@@ -52,6 +52,7 @@ public:
   INLINE static string get_arg(int n);
 
   INLINE static string get_binary_name();
+  INLINE static string get_dtool_name();
 
   static Filename get_cwd();
 
@@ -66,6 +67,7 @@ private:
   string ns_get_arg(int n) const;
 
   string ns_get_binary_name() const;
+  string ns_get_dtool_name() const;
 
   static ExecutionEnvironment *get_ptr();
 
@@ -80,6 +82,7 @@ private:
   CommandArguments _args;
 
   string _binary_name;
+  string _dtool_name;
 
   static ExecutionEnvironment *_global_ptr;
 };
diff --git a/dtool/src/prc/configPageManager.cxx b/dtool/src/prc/configPageManager.cxx
index 24b8cfdb39..735de4207d 100644
--- a/dtool/src/prc/configPageManager.cxx
+++ b/dtool/src/prc/configPageManager.cxx
@@ -153,7 +153,7 @@ reload_implicit_pages() {
       }
     }
   }
-
+  
   // PRC_PATH_ENVVARS lists one or more environment variables separated
   // by spaces.  Pull them out, and then each one of those contains a
   // list of directories to search.  Add each of those to the search
@@ -163,13 +163,22 @@ reload_implicit_pages() {
     vector_string prc_path_envvar_list;
     ConfigDeclaration::extract_words(prc_path_envvars, prc_path_envvar_list);
     for (size_t i = 0; i < prc_path_envvar_list.size(); ++i) {
-      string prc_path = ExecutionEnvironment::get_environment_variable(prc_path_envvar_list[i]);
-      if (!prc_path.empty()) {
-        _search_path.append_path(prc_path);
+      string path = ExecutionEnvironment::get_environment_variable(prc_path_envvar_list[i]);
+      size_t p = 0;
+      while (p < path.length()) {
+        size_t q = path.find_first_of(DEFAULT_PATHSEP, p);
+        if (q == string::npos) {
+          q = path.length();
+        }
+        Filename prc_dir_filename = path.substr(p, q - p);
+        if (scan_auto_prc_dir(prc_dir_filename)) {
+          _search_path.append_directory(prc_dir_filename);
+        }
+        p = q + 1;
       }
     }
   }
-
+  
   if (_search_path.is_empty()) {
     // If nothing's on the search path (PRC_DIR and PRC_PATH were not
     // defined), then use the DEFAULT_PRC_DIR.
@@ -444,8 +453,8 @@ scan_auto_prc_dir(Filename &prc_dir) const {
     Filename suffix = prc_dir_string.substr(6);
     
     // Start at the executable directory.
-    Filename binary = ExecutionEnvironment::get_binary_name();
-    Filename dir = binary.get_dirname();
+    Filename dtool = ExecutionEnvironment::get_dtool_name();
+    Filename dir = dtool.get_dirname();
 
     if (scan_up_from(prc_dir, dir, suffix)) {
       return true;
diff --git a/dtool/src/prc/configVariableEnum.I b/dtool/src/prc/configVariableEnum.I
index e1bf32545d..dcee1c8cdb 100644
--- a/dtool/src/prc/configVariableEnum.I
+++ b/dtool/src/prc/configVariableEnum.I
@@ -47,7 +47,7 @@ ConfigVariableEnum(const string &name, EnumType default_value,
 ////////////////////////////////////////////////////////////////////
 template<class EnumType>
 INLINE ConfigVariableEnum<EnumType>::
-ConfigVariableEnum(const string &name, const string &adefault_value, 
+ConfigVariableEnum(const string &name, const string &default_value, 
                    const string &description, int flags) :
 #ifdef PRC_SAVE_DESCRIPTIONS
   ConfigVariable(name, ConfigVariableCore::VT_enum, description, flags),