diff --exclude=CVS -urN CMake.orig/Docs/cmake-syntax.vim CMake/Docs/cmake-syntax.vim
--- CMake.orig/Docs/cmake-syntax.vim	2008-01-16 11:53:53.000000000 -0500
+++ CMake/Docs/cmake-syntax.vim	2008-08-20 01:34:36.000000000 -0400
@@ -3,7 +3,7 @@
 "   Program:   CMake - Cross-Platform Makefile Generator
 "   Module:    $RCSfile: cmake-syntax.vim,v $
 "   Language:  VIM
-"   Date:      $Date: 2008-01-16 16:53:53 $
+"   Date:      $Date: 2008/01/16 16:53:53 $
 "   Version:   $Revision: 1.9 $
 "
 " =============================================================================
@@ -12,7 +12,7 @@
 " Language:     CMake
 " Author:       Andy Cedilnik <andy.cedilnik@kitware.com>
 " Maintainer:   Karthik Krishnan <karthik.krishnan@kitware.com>
-" Last Change:  $Date: 2008-01-16 16:53:53 $
+" Last Change:  $Date: 2008/01/16 16:53:53 $
 " Version:      $Revision: 1.9 $
 "
 " Licence:      The CMake license applies to this file. See
@@ -41,7 +41,7 @@
 syn region cmakeArguments start=/(/ end=/)/ 
             \ contains=ALLBUT,cmakeArguments,cmakeTodo
 syn keyword cmakeSystemVariables
-            \ WIN32 UNIX APPLE CYGWIN BORLAND MINGW MSVC MSVC_IDE MSVC60 MSVC70 MSVC71 MSVC80
+            \ WIN32 UNIX APPLE CYGWIN BORLAND MINGW MSVC MSVC_IDE MSVC60 MSVC70 MSVC71 MSVC80 MSVC90
 syn keyword cmakeOperators
             \ ABSOLUTE AND BOOL CACHE COMMAND DEFINED DOC EQUAL EXISTS EXT FALSE GREATER INTERNAL LESS MATCHES NAME NAMES NAME_WE NOT OFF ON OR PATH PATHS PROGRAM STREQUAL STRGREATER STRING STRLESS TRUE
             \ contained
@@ -50,7 +50,7 @@
 
 " The keywords are generated as:  cmake --help-command-list | tr "\n" " "
 syn keyword cmakeStatement 
-      \ ADD_CUSTOM_COMMAND ADD_CUSTOM_TARGET ADD_DEFINITIONS ADD_DEPENDENCIES ADD_EXECUTABLE ADD_LIBRARY ADD_SUBDIRECTORY ADD_TEST AUX_SOURCE_DIRECTORY BUILD_COMMAND BUILD_NAME CMAKE_MINIMUM_REQUIRED CONFIGURE_FILE CREATE_TEST_SOURCELIST ELSE ELSEIF ENABLE_LANGUAGE ENABLE_TESTING ENDFOREACH ENDFUNCTION ENDIF ENDMACRO ENDWHILE EXEC_PROGRAM EXECUTE_PROCESS EXPORT_LIBRARY_DEPENDENCIES FILE FIND_FILE FIND_LIBRARY FIND_PACKAGE FIND_PATH FIND_PROGRAM FLTK_WRAP_UI FOREACH FUNCTION GET_CMAKE_PROPERTY GET_DIRECTORY_PROPERTY GET_FILENAME_COMPONENT GET_SOURCE_FILE_PROPERTY GET_TARGET_PROPERTY GET_TEST_PROPERTY IF INCLUDE INCLUDE_DIRECTORIES INCLUDE_EXTERNAL_MSPROJECT INCLUDE_REGULAR_EXPRESSION INSTALL INSTALL_FILES INSTALL_PROGRAMS INSTALL_TARGETS LINK_DIRECTORIES LINK_LIBRARIES LIST LOAD_CACHE LOAD_COMMAND MACRO MAKE_DIRECTORY MARK_AS_ADVANCED MATH MESSAGE OPTION OUTPUT_REQUIRED_FILES PROJECT QT_WRAP_CPP QT_WRAP_UI REMOVE REMOVE_DEFINITIONS SEPARATE_ARGUMENTS SET SET_DIRECTORY_PROPERTIES SET_SOURCE_FILES_PROPERTIES SET_TARGET_PROPERTIES SET_TESTS_PROPERTIES SITE_NAME SOURCE_GROUP STRING SUBDIR_DEPENDS SUBDIRS TARGET_LINK_LIBRARIES TRY_COMPILE TRY_RUN USE_MANGLED_MESA UTILITY_SOURCE VARIABLE_REQUIRES VTK_MAKE_INSTANTIATOR VTK_WRAP_JAVA VTK_WRAP_PYTHON VTK_WRAP_TCL WHILE WRITE_FILE
+      \ ADD_CUSTOM_COMMAND ADD_CUSTOM_TARGET ADD_DEFINITIONS ADD_DEPENDENCIES ADD_EXECUTABLE ADD_LIBRARY ADD_SUBDIRECTORY ADD_TEST AUX_SOURCE_DIRECTORY BUILD_COMMAND BUILD_NAME CMAKE_MINIMUM_REQUIRED CONFIGURE_FILE CREATE_TEST_SOURCELIST ELSE ELSEIF ENABLE_LANGUAGE ENABLE_TESTING ENDFOREACH ENDFUNCTION ENDIF ENDMACRO ENDWHILE EXEC_PROGRAM EXECUTE_PROCESS EXPORT_LIBRARY_DEPENDENCIES FILE FIND_FILE FIND_LIBRARY FIND_PACKAGE FIND_PATH FIND_PROGRAM FLTK_WRAP_UI FOREACH FUNCTION GET_CMAKE_PROPERTY GET_DIRECTORY_PROPERTY GET_FILENAME_COMPONENT GET_SOURCE_FILE_PROPERTY GET_TARGET_PROPERTY GET_TEST_PROPERTY IF INCLUDE INCLUDE_DIRECTORIES INCLUDE_EXTERNAL_MSPROJECT INCLUDE_REGULAR_EXPRESSION INSTALL INSTALL_FILES INSTALL_PROGRAMS INSTALL_TARGETS LINK_DIRECTORIES LINK_LIBRARIES LIST LOAD_CACHE LOAD_COMMAND MACRO MAKE_DIRECTORY MARK_AS_ADVANCED MATH MESSAGE OPTION OUTPUT_REQUIRED_FILES PROJECT QT_WRAP_CPP QT_WRAP_UI REMOVE REMOVE_DEFINITIONS SEPARATE_ARGUMENTS SET SET_DIRECTORY_PROPERTIES SET_SOURCE_FILES_PROPERTIES SET_TARGET_PROPERTIES SET_TESTS_PROPERTIES SITE_NAME SOURCE_GROUP STRING SUBDIR_DEPENDS SUBDIRS TARGET_LINK_LIBRARIES TRY_COMPILE TRY_RUN UNSET USE_MANGLED_MESA UTILITY_SOURCE VARIABLE_REQUIRES VTK_MAKE_INSTANTIATOR VTK_WRAP_JAVA VTK_WRAP_PYTHON VTK_WRAP_TCL WHILE WRITE_FILE
             \ nextgroup=cmakeArguments
 syn keyword cmakeTodo 
             \ TODO FIXME XXX 
diff --exclude=CVS -urN CMake.orig/Source/cmake.cxx CMake/Source/cmake.cxx
--- CMake.orig/Source/cmake.cxx	2008-08-19 13:31:21.000000000 -0400
+++ CMake/Source/cmake.cxx	2008-08-20 01:34:59.000000000 -0400
@@ -437,7 +437,7 @@
           currentEntry != entriesToDelete.end();
           ++currentEntry)
         {
-        this->CacheManager->RemoveCacheEntry(currentEntry->c_str());
+        this->CacheManager->RemoveCacheEntry(currentEntry->c_str(), true);
         }
       }
     else if(arg.find("-C",0) == 0)
@@ -2145,8 +2145,8 @@
     {
     // We must have a bad generator selection.  Wipe the cache entry so the
     // user can select another.
-    this->CacheManager->RemoveCacheEntry("CMAKE_GENERATOR");
-    this->CacheManager->RemoveCacheEntry("CMAKE_EXTRA_GENERATOR");
+    this->CacheManager->RemoveCacheEntry("CMAKE_GENERATOR", true);
+    this->CacheManager->RemoveCacheEntry("CMAKE_EXTRA_GENERATOR", true);
     }
   // only save the cache if there were no fatal errors
   if ( !this->ScriptMode )
diff --exclude=CVS -urN CMake.orig/Source/cmBootstrapCommands.cxx CMake/Source/cmBootstrapCommands.cxx
--- CMake.orig/Source/cmBootstrapCommands.cxx	2008-07-07 15:07:54.000000000 -0400
+++ CMake/Source/cmBootstrapCommands.cxx	2008-08-20 01:34:59.000000000 -0400
@@ -93,6 +93,7 @@
 #include "cmTargetLinkLibrariesCommand.cxx"
 #include "cmTryCompileCommand.cxx"
 #include "cmTryRunCommand.cxx"
+#include "cmUnsetCommand.cxx"
 
 void GetBootstrapCommands(std::list<cmCommand*>& commands)
 {
@@ -163,4 +164,5 @@
   commands.push_back(new cmTargetLinkLibrariesCommand);
   commands.push_back(new cmTryCompileCommand);
   commands.push_back(new cmTryRunCommand);
+  commands.push_back(new cmUnsetCommand);
 }
diff --exclude=CVS -urN CMake.orig/Source/cmCacheManager.cxx CMake/Source/cmCacheManager.cxx
--- CMake.orig/Source/cmCacheManager.cxx	2008-01-29 17:30:48.000000000 -0500
+++ CMake/Source/cmCacheManager.cxx	2008-08-20 01:34:59.000000000 -0400
@@ -3,7 +3,7 @@
   Program:   CMake - Cross-Platform Makefile Generator
   Module:    $RCSfile: cmCacheManager.cxx,v $
   Language:  C++
-  Date:      $Date: 2008-01-29 22:30:48 $
+  Date:      $Date: 2008/01/29 22:30:48 $
   Version:   $Revision: 1.100 $
 
   Copyright (c) 2002 Kitware, Inc., Insight Consortium.  All rights reserved.
@@ -707,14 +707,14 @@
     }
 }
 
-void cmCacheManager::RemoveCacheEntry(const char* key)
+void cmCacheManager::RemoveCacheEntry(const char* key, bool warn)
 {
   CacheEntryMap::iterator i = this->Cache.find(key);
   if(i != this->Cache.end())
     {
     this->Cache.erase(i);
     }
-  else
+  else if (warn)
     {
     std::cerr << "Failed to remove entry:" << key << std::endl;
     }
diff --exclude=CVS -urN CMake.orig/Source/cmCacheManager.h CMake/Source/cmCacheManager.h
--- CMake.orig/Source/cmCacheManager.h	2008-03-07 11:43:47.000000000 -0500
+++ CMake/Source/cmCacheManager.h	2008-08-20 01:34:59.000000000 -0400
@@ -125,7 +125,7 @@
   cmCacheManager::CacheIterator GetCacheIterator(const char *key=0);
   
   ///! Remove an entry from the cache
-  void RemoveCacheEntry(const char* key);
+  void RemoveCacheEntry(const char* key, bool warn);
   
   ///! Get the number of entries in the cache
   int GetSize() {
diff --exclude=CVS -urN CMake.orig/Source/cmMakefile.cxx CMake/Source/cmMakefile.cxx
--- CMake.orig/Source/cmMakefile.cxx	2008-08-19 10:28:22.000000000 -0400
+++ CMake/Source/cmMakefile.cxx	2008-08-20 01:34:59.000000000 -0400
@@ -1648,6 +1648,11 @@
 #endif
 }
 
+void cmMakefile::RemoveCacheDefinition(const char* name)
+{
+  this->GetCacheManager()->RemoveCacheEntry(name, false);
+}
+
 void cmMakefile::SetProjectName(const char* p)
 {
   this->ProjectName = p;
diff --exclude=CVS -urN CMake.orig/Source/cmMakefile.h CMake/Source/cmMakefile.h
--- CMake.orig/Source/cmMakefile.h	2008-08-18 16:29:00.000000000 -0400
+++ CMake/Source/cmMakefile.h	2008-08-20 01:34:59.000000000 -0400
@@ -278,6 +278,8 @@
    * for cache entries, and will only affect the current makefile.
    */
   void RemoveDefinition(const char* name);
+  ///! Remove a definition from this makefile and the global cmake cache.
+  void RemoveCacheDefinition(const char* name);
   
   /**
    * Specify the name of the project for this build.
diff --exclude=CVS -urN CMake.orig/Source/cmUnsetCommand.cxx CMake/Source/cmUnsetCommand.cxx
--- CMake.orig/Source/cmUnsetCommand.cxx	1969-12-31 19:00:00.000000000 -0500
+++ CMake/Source/cmUnsetCommand.cxx	2008-08-20 01:34:12.000000000 -0400
@@ -0,0 +1,53 @@
+/*=========================================================================
+
+  Program:   CMake - Cross-Platform Makefile Generator
+  Module:    $RCSfile: cmSetCommand.cxx,v $
+  Language:  C++
+  Date:      $Date: 2008-03-13 17:52:49 $
+  Version:   $Revision: 1.33 $
+
+  Copyright (c) 2002 Kitware, Inc., Insight Consortium.  All rights reserved.
+  See Copyright.txt or http://www.cmake.org/HTML/Copyright.html for details.
+
+     This software is distributed WITHOUT ANY WARRANTY; without even 
+     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR 
+     PURPOSE.  See the above copyright notices for more information.
+
+=========================================================================*/
+#include "cmUnsetCommand.h"
+
+// cmUnsetCommand
+bool cmUnsetCommand::InitialPass(std::vector<std::string> const& args, cmExecutionStatus &)
+{
+  if(args.size() != 1 )
+    {
+    this->SetError("called with incorrect number of arguments");
+    return false;
+    }
+  
+  // watch for ENV signatures
+  const char* variable = args[0].c_str(); // VAR is always first
+  if (!strncmp(variable,"ENV{",4) && strlen(variable) > 5)
+    {
+    // what is the variable name
+    char *varName = new char [strlen(variable)];
+    strncpy(varName,variable+4,strlen(variable)-5);
+    varName[strlen(variable)-5] = '\0';
+
+#ifdef CMAKE_BUILD_WITH_CMAKE
+    cmSystemTools::UnsetEnv(varName);
+#endif
+    return true;
+    }
+  
+  // UNSET (VAR)
+  if (args.size() == 1)
+    {
+    this->Makefile->RemoveDefinition(args[0].c_str());
+    this->Makefile->RemoveCacheDefinition(args[0].c_str());
+    return true;
+    }
+
+  return false;
+}
+
diff --exclude=CVS -urN CMake.orig/Source/cmUnsetCommand.h CMake/Source/cmUnsetCommand.h
--- CMake.orig/Source/cmUnsetCommand.h	1969-12-31 19:00:00.000000000 -0500
+++ CMake/Source/cmUnsetCommand.h	2008-08-20 01:34:12.000000000 -0400
@@ -0,0 +1,78 @@
+/*=========================================================================
+
+  Program:   CMake - Cross-Platform Makefile Generator
+  Module:    $RCSfile: cmSetCommand.h,v $
+  Language:  C++
+  Date:      $Date: 2008/01/23 15:27:59 $
+  Version:   $Revision: 1.20 $
+
+  Copyright (c) 2002 Kitware, Inc., Insight Consortium.  All rights reserved.
+  See Copyright.txt or http://www.cmake.org/HTML/Copyright.html for details.
+
+     This software is distributed WITHOUT ANY WARRANTY; without even 
+     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR 
+     PURPOSE.  See the above copyright notices for more information.
+
+=========================================================================*/
+#ifndef cmUnsetCommand_h
+#define cmUnsetCommand_h
+
+#include "cmCommand.h"
+
+/** \class cmUnsetCommand
+ * \brief Unset a CMAKE variable
+ *
+ * cmUnsetCommand unsets or removes a variable.
+ */
+class cmUnsetCommand : public cmCommand
+{
+public:
+  /**
+   * This is a virtual constructor for the command.
+   */
+  virtual cmCommand* Clone() 
+    {
+    return new cmUnsetCommand;
+    }
+
+  /**
+   * This is called when the command is first encountered in
+   * the CMakeLists.txt file.
+   */
+  virtual bool InitialPass(std::vector<std::string> const& args,
+                           cmExecutionStatus &status);
+
+  /**
+   * This determines if the command is invoked when in script mode.
+   */
+  virtual bool IsScriptable() { return true; }
+
+  /**
+   * The name of the command as specified in CMakeList.txt.
+   */
+  virtual const char* GetName() {return "unset";}
+  
+  /**
+   * Succinct documentation.
+   */
+  virtual const char* GetTerseDocumentation() 
+    {
+    return "Unset a variable or cache variable causing it to become undefined.";
+    }
+  
+  /**
+   * More documentation.
+   */
+  virtual const char* GetFullDocumentation()
+    {
+    return
+      "  unset(<variable>)\n"
+      "Removes the specified variable or cache variable causing it to become undefined.";
+    }
+  
+  cmTypeMacro(cmUnsetCommand, cmCommand);
+};
+
+
+
+#endif
diff --exclude=CVS -urN CMake.orig/Source/CursesDialog/cmCursesMainForm.cxx CMake/Source/CursesDialog/cmCursesMainForm.cxx
--- CMake.orig/Source/CursesDialog/cmCursesMainForm.cxx	2008-03-07 16:32:09.000000000 -0500
+++ CMake/Source/CursesDialog/cmCursesMainForm.cxx	2008-08-20 01:35:22.000000000 -0400
@@ -1139,7 +1139,7 @@
             field_userptr(this->Fields[findex-2]));
         if ( lbl )
           {
-          this->CMakeInstance->GetCacheManager()->RemoveCacheEntry(lbl->GetValue());
+          this->CMakeInstance->GetCacheManager()->RemoveCacheEntry(lbl->GetValue(), true);
 
           std::string nextVal;
           if (nextCur)
diff --exclude=CVS -urN CMake.orig/Source/FLTKDialog/FLTKPropertyItemRow.cxx CMake/Source/FLTKDialog/FLTKPropertyItemRow.cxx
--- CMake.orig/Source/FLTKDialog/FLTKPropertyItemRow.cxx	2007-08-21 16:21:09.000000000 -0400
+++ CMake/Source/FLTKDialog/FLTKPropertyItemRow.cxx	2008-08-20 01:36:25.000000000 -0400
@@ -3,7 +3,7 @@
   Program:   Insight Segmentation & Registration Toolkit
   Module:    $RCSfile: FLTKPropertyItemRow.cxx,v $
   Language:  C++
-  Date:      $Date: 2007-08-21 20:21:09 $
+  Date:      $Date: 2007/08/21 20:21:09 $
   Version:   $Revision: 1.20 $
 
   Copyright (c) 2002 Insight Consortium. All rights reserved.
@@ -238,7 +238,7 @@
       if( answer == 1 )
       {
         // Remove the entry from the cache
-        m_CMakeSetup->GetCMakeInstance()->GetCacheManager()->RemoveCacheEntry(propertyName);
+        m_CMakeSetup->GetCMakeInstance()->GetCacheManager()->RemoveCacheEntry(propertyName, true);
           // Get the parent: Fl_Tile that manages the whole row in the GUI
         Fl_Group * parentGroup      = dynamic_cast<Fl_Group *>(button->parent());
         // Get the grandParent: Fl_Pack with the property list
diff --exclude=CVS -urN CMake.orig/Source/FLTKDialog/FLTKPropertyList.cxx CMake/Source/FLTKDialog/FLTKPropertyList.cxx
--- CMake.orig/Source/FLTKDialog/FLTKPropertyList.cxx	2007-08-21 16:21:09.000000000 -0400
+++ CMake/Source/FLTKDialog/FLTKPropertyList.cxx	2008-08-20 01:36:25.000000000 -0400
@@ -3,7 +3,7 @@
   Program:   Insight Segmentation & Registration Toolkit
   Module:    $RCSfile: FLTKPropertyList.cxx,v $
   Language:  C++
-  Date:      $Date: 2007-08-21 20:21:09 $
+  Date:      $Date: 2007/08/21 20:21:09 $
   Version:   $Revision: 1.10 $
 
   Copyright (c) 2002 Insight Consortium. All rights reserved.
@@ -139,7 +139,7 @@
   for(int i =0; i < c; ++i)
     {
     PropertyItem* pItem = (PropertyItem*) GetItemDataPtr(0);
-//    cmCacheManager::GetInstance()->RemoveCacheEntry(pItem->m_propName.c_str());
+//    cmCacheManager::GetInstance()->RemoveCacheEntry(pItem->m_propName.c_str(), true);
     m_PropertyItems.erase(pItem);
     delete pItem;
     }
diff --exclude=CVS -urN CMake.orig/Source/MFCDialog/PropertyList.cpp CMake/Source/MFCDialog/PropertyList.cpp
--- CMake.orig/Source/MFCDialog/PropertyList.cpp	2007-03-05 09:51:13.000000000 -0500
+++ CMake/Source/MFCDialog/PropertyList.cpp	2008-08-20 01:36:58.000000000 -0400
@@ -729,7 +729,7 @@
     return;
     }
   CPropertyItem* pItem = (CPropertyItem*) GetItemDataPtr(m_curSel);
-  m_CMakeSetupDialog->GetCMakeInstance()->GetCacheManager()->RemoveCacheEntry(pItem->m_propName);
+  m_CMakeSetupDialog->GetCMakeInstance()->GetCacheManager()->RemoveCacheEntry(pItem->m_propName, true);
   m_PropertyItems.erase(pItem);
   delete pItem; 
   this->DeleteString(m_curSel);
diff --exclude=CVS -urN CMake.orig/Source/QtDialog/QCMake.cxx CMake/Source/QtDialog/QCMake.cxx
--- CMake.orig/Source/QtDialog/QCMake.cxx	2008-05-15 19:21:01.000000000 -0400
+++ CMake/Source/QtDialog/QCMake.cxx	2008-08-20 01:37:08.000000000 -0400
@@ -209,7 +209,7 @@
   // remove some properites
   foreach(QString s, toremove)
     {
-    cachem->RemoveCacheEntry(s.toAscii().data());
+    cachem->RemoveCacheEntry(s.toAscii().data(), true);
     }
   
   // add some new properites
diff --exclude=CVS -urN CMake.orig/Source/WXDialog/PropertyList.cpp CMake/Source/WXDialog/PropertyList.cpp
--- CMake.orig/Source/WXDialog/PropertyList.cpp	2005-06-30 15:54:14.000000000 -0400
+++ CMake/Source/WXDialog/PropertyList.cpp	2008-08-20 01:37:30.000000000 -0400
@@ -3,7 +3,7 @@
   Program:   WXDialog - wxWidgets X-platform GUI Front-End for CMake
   Module:    $RCSfile: PropertyList.cpp,v $
   Language:  C++
-  Date:      $Date: 2005-06-30 19:54:14 $
+  Date:      $Date: 2005/06/30 19:54:14 $
   Version:   $Revision: 1.1 $
 
   Author:    Jorgen Bodde
@@ -486,7 +486,7 @@
     return;
     }
   wxPropertyItem* pItem = (wxPropertyItem*) GetItemDataPtr(m_curSel);
-  m_CMakeSetupDialog->GetCMakeInstance()->GetCacheManager()->RemoveCacheEntry(pItem->m_propName);
+  m_CMakeSetupDialog->GetCMakeInstance()->GetCacheManager()->RemoveCacheEntry(pItem->m_propName, true);
   m_PropertyItems.erase(pItem);
   delete pItem; 
   this->DeleteString(m_curSel);
diff --exclude=CVS -urN CMake.orig/Tests/Unset/CMakeLists.txt CMake/Tests/Unset/CMakeLists.txt
--- CMake.orig/Tests/Unset/CMakeLists.txt	1969-12-31 19:00:00.000000000 -0500
+++ CMake/Tests/Unset/CMakeLists.txt	2008-08-20 01:08:04.000000000 -0400
@@ -0,0 +1,31 @@
+project(Unset)
+
+# Local variable
+
+set(x 42)
+if(NOT x EQUAL 42)
+    message(FATAL_ERROR "x!=42")
+endif(NOT x EQUAL 42)
+
+if(NOT DEFINED x)
+    message(FATAL_ERROR "x should be defined!")
+endif(NOT DEFINED x)
+
+unset(x)
+if(DEFINED x)
+    message(FATAL_ERROR "x should be undefined now!")
+endif(DEFINED x)
+
+# Cache variable
+
+set(BAR "test" CACHE STRING "documentation")
+if(NOT DEFINED BAR)
+    message(FATAL_ERROR "BAR not defined")
+endif(NOT DEFINED BAR)
+
+unset(BAR)
+if(DEFINED BAR)
+    message(FATAL_ERROR "BAR still defined")
+endif(DEFINED BAR)
+
+add_executable(Unset unset.cc)
diff --exclude=CVS -urN CMake.orig/Tests/Unset/unset.cc CMake/Tests/Unset/unset.cc
--- CMake.orig/Tests/Unset/unset.cc	1969-12-31 19:00:00.000000000 -0500
+++ CMake/Tests/Unset/unset.cc	2008-08-20 01:08:04.000000000 -0400
@@ -0,0 +1,4 @@
+int main()
+{
+   return 0;
+}

diff --exclude=CVS -Nur CMake.orig/Docs/cmake-syntax.vim CMake/Docs/cmake-syntax.vim
--- CMake.orig/Docs/cmake-syntax.vim	2008-01-16 11:53:53.000000000 -0500
+++ CMake/Docs/cmake-syntax.vim	2008-08-20 01:34:36.000000000 -0400
@@ -3,7 +3,7 @@
 "   Program:   CMake - Cross-Platform Makefile Generator
 "   Module:    $RCSfile: cmake-syntax.vim,v $
 "   Language:  VIM
-"   Date:      $Date: 2008-01-16 16:53:53 $
+"   Date:      $Date: 2008/01/16 16:53:53 $
 "   Version:   $Revision: 1.9 $
 "
 " =============================================================================
@@ -12,7 +12,7 @@
 " Language:     CMake
 " Author:       Andy Cedilnik <andy.cedilnik@kitware.com>
 " Maintainer:   Karthik Krishnan <karthik.krishnan@kitware.com>
-" Last Change:  $Date: 2008-01-16 16:53:53 $
+" Last Change:  $Date: 2008/01/16 16:53:53 $
 " Version:      $Revision: 1.9 $
 "
 " Licence:      The CMake license applies to this file. See
@@ -41,7 +41,7 @@
 syn region cmakeArguments start=/(/ end=/)/ 
             \ contains=ALLBUT,cmakeArguments,cmakeTodo
 syn keyword cmakeSystemVariables
-            \ WIN32 UNIX APPLE CYGWIN BORLAND MINGW MSVC MSVC_IDE MSVC60 MSVC70 MSVC71 MSVC80
+            \ WIN32 UNIX APPLE CYGWIN BORLAND MINGW MSVC MSVC_IDE MSVC60 MSVC70 MSVC71 MSVC80 MSVC90
 syn keyword cmakeOperators
             \ ABSOLUTE AND BOOL CACHE COMMAND DEFINED DOC EQUAL EXISTS EXT FALSE GREATER INTERNAL LESS MATCHES NAME NAMES NAME_WE NOT OFF ON OR PATH PATHS PROGRAM STREQUAL STRGREATER STRING STRLESS TRUE
             \ contained
@@ -50,7 +50,7 @@
 
 " The keywords are generated as:  cmake --help-command-list | tr "\n" " "
 syn keyword cmakeStatement 
-      \ ADD_CUSTOM_COMMAND ADD_CUSTOM_TARGET ADD_DEFINITIONS ADD_DEPENDENCIES ADD_EXECUTABLE ADD_LIBRARY ADD_SUBDIRECTORY ADD_TEST AUX_SOURCE_DIRECTORY BUILD_COMMAND BUILD_NAME CMAKE_MINIMUM_REQUIRED CONFIGURE_FILE CREATE_TEST_SOURCELIST ELSE ELSEIF ENABLE_LANGUAGE ENABLE_TESTING ENDFOREACH ENDFUNCTION ENDIF ENDMACRO ENDWHILE EXEC_PROGRAM EXECUTE_PROCESS EXPORT_LIBRARY_DEPENDENCIES FILE FIND_FILE FIND_LIBRARY FIND_PACKAGE FIND_PATH FIND_PROGRAM FLTK_WRAP_UI FOREACH FUNCTION GET_CMAKE_PROPERTY GET_DIRECTORY_PROPERTY GET_FILENAME_COMPONENT GET_SOURCE_FILE_PROPERTY GET_TARGET_PROPERTY GET_TEST_PROPERTY IF INCLUDE INCLUDE_DIRECTORIES INCLUDE_EXTERNAL_MSPROJECT INCLUDE_REGULAR_EXPRESSION INSTALL INSTALL_FILES INSTALL_PROGRAMS INSTALL_TARGETS LINK_DIRECTORIES LINK_LIBRARIES LIST LOAD_CACHE LOAD_COMMAND MACRO MAKE_DIRECTORY MARK_AS_ADVANCED MATH MESSAGE OPTION OUTPUT_REQUIRED_FILES PROJECT QT_WRAP_CPP QT_WRAP_UI REMOVE REMOVE_DEFINITIONS SEPARATE_ARGUMENTS SET SET_DIRECTORY_PROPERTIES SET_SOURCE_FILES_PROPERTIES SET_TARGET_PROPERTIES SET_TESTS_PROPERTIES SITE_NAME SOURCE_GROUP STRING SUBDIR_DEPENDS SUBDIRS TARGET_LINK_LIBRARIES TRY_COMPILE TRY_RUN USE_MANGLED_MESA UTILITY_SOURCE VARIABLE_REQUIRES VTK_MAKE_INSTANTIATOR VTK_WRAP_JAVA VTK_WRAP_PYTHON VTK_WRAP_TCL WHILE WRITE_FILE
+      \ ADD_CUSTOM_COMMAND ADD_CUSTOM_TARGET ADD_DEFINITIONS ADD_DEPENDENCIES ADD_EXECUTABLE ADD_LIBRARY ADD_SUBDIRECTORY ADD_TEST AUX_SOURCE_DIRECTORY BUILD_COMMAND BUILD_NAME CMAKE_MINIMUM_REQUIRED CONFIGURE_FILE CREATE_TEST_SOURCELIST ELSE ELSEIF ENABLE_LANGUAGE ENABLE_TESTING ENDFOREACH ENDFUNCTION ENDIF ENDMACRO ENDWHILE EXEC_PROGRAM EXECUTE_PROCESS EXPORT_LIBRARY_DEPENDENCIES FILE FIND_FILE FIND_LIBRARY FIND_PACKAGE FIND_PATH FIND_PROGRAM FLTK_WRAP_UI FOREACH FUNCTION GET_CMAKE_PROPERTY GET_DIRECTORY_PROPERTY GET_FILENAME_COMPONENT GET_SOURCE_FILE_PROPERTY GET_TARGET_PROPERTY GET_TEST_PROPERTY IF INCLUDE INCLUDE_DIRECTORIES INCLUDE_EXTERNAL_MSPROJECT INCLUDE_REGULAR_EXPRESSION INSTALL INSTALL_FILES INSTALL_PROGRAMS INSTALL_TARGETS LINK_DIRECTORIES LINK_LIBRARIES LIST LOAD_CACHE LOAD_COMMAND MACRO MAKE_DIRECTORY MARK_AS_ADVANCED MATH MESSAGE OPTION OUTPUT_REQUIRED_FILES PROJECT QT_WRAP_CPP QT_WRAP_UI REMOVE REMOVE_DEFINITIONS SEPARATE_ARGUMENTS SET SET_DIRECTORY_PROPERTIES SET_SOURCE_FILES_PROPERTIES SET_TARGET_PROPERTIES SET_TESTS_PROPERTIES SITE_NAME SOURCE_GROUP STRING SUBDIR_DEPENDS SUBDIRS TARGET_LINK_LIBRARIES TRY_COMPILE TRY_RUN UNSET USE_MANGLED_MESA UTILITY_SOURCE VARIABLE_REQUIRES VTK_MAKE_INSTANTIATOR VTK_WRAP_JAVA VTK_WRAP_PYTHON VTK_WRAP_TCL WHILE WRITE_FILE
             \ nextgroup=cmakeArguments
 syn keyword cmakeTodo 
             \ TODO FIXME XXX 
diff --exclude=CVS -Nur CMake.orig/Source/cmake.cxx CMake/Source/cmake.cxx
--- CMake.orig/Source/cmake.cxx	2008-08-19 13:31:21.000000000 -0400
+++ CMake/Source/cmake.cxx	2008-08-20 01:34:59.000000000 -0400
@@ -437,7 +437,7 @@
           currentEntry != entriesToDelete.end();
           ++currentEntry)
         {
-        this->CacheManager->RemoveCacheEntry(currentEntry->c_str());
+        this->CacheManager->RemoveCacheEntry(currentEntry->c_str(), true);
         }
       }
     else if(arg.find("-C",0) == 0)
@@ -2145,8 +2145,8 @@
     {
     // We must have a bad generator selection.  Wipe the cache entry so the
     // user can select another.
-    this->CacheManager->RemoveCacheEntry("CMAKE_GENERATOR");
-    this->CacheManager->RemoveCacheEntry("CMAKE_EXTRA_GENERATOR");
+    this->CacheManager->RemoveCacheEntry("CMAKE_GENERATOR", true);
+    this->CacheManager->RemoveCacheEntry("CMAKE_EXTRA_GENERATOR", true);
     }
   // only save the cache if there were no fatal errors
   if ( !this->ScriptMode )
diff --exclude=CVS -Nur CMake.orig/Source/cmBootstrapCommands.cxx CMake/Source/cmBootstrapCommands.cxx
--- CMake.orig/Source/cmBootstrapCommands.cxx	2008-07-07 15:07:54.000000000 -0400
+++ CMake/Source/cmBootstrapCommands.cxx	2008-08-20 01:34:59.000000000 -0400
@@ -93,6 +93,7 @@
 #include "cmTargetLinkLibrariesCommand.cxx"
 #include "cmTryCompileCommand.cxx"
 #include "cmTryRunCommand.cxx"
+#include "cmUnsetCommand.cxx"
 
 void GetBootstrapCommands(std::list<cmCommand*>& commands)
 {
@@ -163,4 +164,5 @@
   commands.push_back(new cmTargetLinkLibrariesCommand);
   commands.push_back(new cmTryCompileCommand);
   commands.push_back(new cmTryRunCommand);
+  commands.push_back(new cmUnsetCommand);
 }
diff --exclude=CVS -Nur CMake.orig/Source/cmCacheManager.cxx CMake/Source/cmCacheManager.cxx
--- CMake.orig/Source/cmCacheManager.cxx	2008-01-29 17:30:48.000000000 -0500
+++ CMake/Source/cmCacheManager.cxx	2008-08-20 01:34:59.000000000 -0400
@@ -3,7 +3,7 @@
   Program:   CMake - Cross-Platform Makefile Generator
   Module:    $RCSfile: cmCacheManager.cxx,v $
   Language:  C++
-  Date:      $Date: 2008-01-29 22:30:48 $
+  Date:      $Date: 2008/01/29 22:30:48 $
   Version:   $Revision: 1.100 $
 
   Copyright (c) 2002 Kitware, Inc., Insight Consortium.  All rights reserved.
@@ -707,14 +707,14 @@
     }
 }
 
-void cmCacheManager::RemoveCacheEntry(const char* key)
+void cmCacheManager::RemoveCacheEntry(const char* key, bool warn)
 {
   CacheEntryMap::iterator i = this->Cache.find(key);
   if(i != this->Cache.end())
     {
     this->Cache.erase(i);
     }
-  else
+  else if (warn)
     {
     std::cerr << "Failed to remove entry:" << key << std::endl;
     }
diff --exclude=CVS -Nur CMake.orig/Source/cmCacheManager.h CMake/Source/cmCacheManager.h
--- CMake.orig/Source/cmCacheManager.h	2008-03-07 11:43:47.000000000 -0500
+++ CMake/Source/cmCacheManager.h	2008-08-20 01:34:59.000000000 -0400
@@ -125,7 +125,7 @@
   cmCacheManager::CacheIterator GetCacheIterator(const char *key=0);
   
   ///! Remove an entry from the cache
-  void RemoveCacheEntry(const char* key);
+  void RemoveCacheEntry(const char* key, bool warn);
   
   ///! Get the number of entries in the cache
   int GetSize() {
diff --exclude=CVS -Nur CMake.orig/Source/cmMakefile.cxx CMake/Source/cmMakefile.cxx
--- CMake.orig/Source/cmMakefile.cxx	2008-08-19 10:28:22.000000000 -0400
+++ CMake/Source/cmMakefile.cxx	2008-08-21 23:35:58.000000000 -0400
@@ -1648,6 +1648,11 @@
 #endif
 }
 
+void cmMakefile::RemoveCacheDefinition(const char* name)
+{
+  this->GetCacheManager()->RemoveCacheEntry(name, false);
+}
+
 void cmMakefile::SetProjectName(const char* p)
 {
   this->ProjectName = p;
diff --exclude=CVS -Nur CMake.orig/Source/cmMakefile.h CMake/Source/cmMakefile.h
--- CMake.orig/Source/cmMakefile.h	2008-08-18 16:29:00.000000000 -0400
+++ CMake/Source/cmMakefile.h	2008-08-21 23:34:20.000000000 -0400
@@ -278,6 +278,8 @@
    * for cache entries, and will only affect the current makefile.
    */
   void RemoveDefinition(const char* name);
+  ///! Remove a definition from the cache.
+  void RemoveCacheDefinition(const char* name);
   
   /**
    * Specify the name of the project for this build.
diff --exclude=CVS -Nur CMake.orig/Source/cmSetCommand.h CMake/Source/cmSetCommand.h
--- CMake.orig/Source/cmSetCommand.h	2008-01-23 10:27:59.000000000 -0500
+++ CMake/Source/cmSetCommand.h	2008-08-22 00:02:23.000000000 -0400
@@ -87,8 +87,9 @@
       "above the current scope. Each new directory or function creates a new "
       "scope. This command will set the value of a variable into the parent "
       "directory or calling function (whichever is applicable to the case at "
-      "hand) If VALUE is not specified then the variable is removed from the "
-      "parent scope.\n"
+      "hand)\n"
+      "If VALUE is not specified then the variable is removed from the "
+      "current scope.  See also: the unset() command.\n"
       "  set(<variable> <value1> ... <valueN>)\n"
       "In this case <variable> is set to a semicolon separated list of "
       "values.\n"
diff --exclude=CVS -Nur CMake.orig/Source/cmUnsetCommand.cxx CMake/Source/cmUnsetCommand.cxx
--- CMake.orig/Source/cmUnsetCommand.cxx	1969-12-31 19:00:00.000000000 -0500
+++ CMake/Source/cmUnsetCommand.cxx	2008-08-21 23:54:25.000000000 -0400
@@ -0,0 +1,63 @@
+/*=========================================================================
+
+  Program:   CMake - Cross-Platform Makefile Generator
+  Module:    $RCSfile: cmSetCommand.cxx,v $
+  Language:  C++
+  Date:      $Date: 2008-03-13 17:52:49 $
+  Version:   $Revision: 1.33 $
+
+  Copyright (c) 2002 Kitware, Inc., Insight Consortium.  All rights reserved.
+  See Copyright.txt or http://www.cmake.org/HTML/Copyright.html for details.
+
+     This software is distributed WITHOUT ANY WARRANTY; without even 
+     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR 
+     PURPOSE.  See the above copyright notices for more information.
+
+=========================================================================*/
+#include "cmUnsetCommand.h"
+
+// cmUnsetCommand
+bool cmUnsetCommand::InitialPass(std::vector<std::string> const& args, cmExecutionStatus &)
+{
+  if(args.size() < 1 || args.size() > 2)
+    {
+    this->SetError("called with incorrect number of arguments");
+    return false;
+    }
+  
+  const char* variable = args[0].c_str();
+
+  // unset(ENV{VAR})
+  if (!strncmp(variable,"ENV{",4) && strlen(variable) > 5)
+    {
+    // what is the variable name
+    char *envVarName = new char [strlen(variable)];
+    strncpy(envVarName,variable+4,strlen(variable)-5);
+    envVarName[strlen(variable)-5] = '\0';
+
+#ifdef CMAKE_BUILD_WITH_CMAKE
+    cmSystemTools::UnsetEnv(envVarName);
+#endif
+    delete[] envVarName;
+    return true;
+    }
+  // unset(VAR)
+  else if (args.size() == 1)
+    {
+    this->Makefile->RemoveDefinition(variable);
+    return true;
+    }
+  // unset(VAR CACHE)
+  else if ((args.size() == 2) && (args[1] == "CACHE"))
+    {
+    this->Makefile->RemoveCacheDefinition(variable);
+    return true;
+    }
+  // ERROR: second argument isn't CACHE
+  else
+    {
+    this->SetError("unset() called with an invalid second argument");
+    return false;
+    }
+}
+
diff --exclude=CVS -Nur CMake.orig/Source/cmUnsetCommand.h CMake/Source/cmUnsetCommand.h
--- CMake.orig/Source/cmUnsetCommand.h	1969-12-31 19:00:00.000000000 -0500
+++ CMake/Source/cmUnsetCommand.h	2008-08-22 00:03:56.000000000 -0400
@@ -0,0 +1,83 @@
+/*=========================================================================
+
+  Program:   CMake - Cross-Platform Makefile Generator
+  Module:    $RCSfile: cmSetCommand.h,v $
+  Language:  C++
+  Date:      $Date: 2008/01/23 15:27:59 $
+  Version:   $Revision: 1.20 $
+
+  Copyright (c) 2002 Kitware, Inc., Insight Consortium.  All rights reserved.
+  See Copyright.txt or http://www.cmake.org/HTML/Copyright.html for details.
+
+     This software is distributed WITHOUT ANY WARRANTY; without even 
+     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR 
+     PURPOSE.  See the above copyright notices for more information.
+
+=========================================================================*/
+#ifndef cmUnsetCommand_h
+#define cmUnsetCommand_h
+
+#include "cmCommand.h"
+
+/** \class cmUnsetCommand
+ * \brief Unset a CMAKE variable
+ *
+ * cmUnsetCommand unsets or removes a variable.
+ */
+class cmUnsetCommand : public cmCommand
+{
+public:
+  /**
+   * This is a virtual constructor for the command.
+   */
+  virtual cmCommand* Clone() 
+    {
+    return new cmUnsetCommand;
+    }
+
+  /**
+   * This is called when the command is first encountered in
+   * the CMakeLists.txt file.
+   */
+  virtual bool InitialPass(std::vector<std::string> const& args,
+                           cmExecutionStatus &status);
+
+  /**
+   * This determines if the command is invoked when in script mode.
+   */
+  virtual bool IsScriptable() { return true; }
+
+  /**
+   * The name of the command as specified in CMakeList.txt.
+   */
+  virtual const char* GetName() {return "unset";}
+  
+  /**
+   * Succinct documentation.
+   */
+  virtual const char* GetTerseDocumentation() 
+    {
+    return "Unset a variable, cache variable, or environment variable, causing it to become undefined.";
+    }
+  
+  /**
+   * More documentation.
+   */
+  virtual const char* GetFullDocumentation()
+    {
+    return
+      "  unset(<variable> [CACHE])\n"
+      "Removes the specified variable if it exists causing it to become undefined.  "
+      "If CACHE is present then a cache variable with the specified name is removed if "
+      "it exists.\n"
+      "<variable> can be an environment variable such as:\n"
+      "  unset( ENV{LD_LIBRARY_PATH} )\n"
+      "in which case the environment variable will be unset if it exists.";
+    }
+  
+  cmTypeMacro(cmUnsetCommand, cmCommand);
+};
+
+
+
+#endif
diff --exclude=CVS -Nur CMake.orig/Source/CursesDialog/cmCursesMainForm.cxx CMake/Source/CursesDialog/cmCursesMainForm.cxx
--- CMake.orig/Source/CursesDialog/cmCursesMainForm.cxx	2008-03-07 16:32:09.000000000 -0500
+++ CMake/Source/CursesDialog/cmCursesMainForm.cxx	2008-08-20 01:35:22.000000000 -0400
@@ -1139,7 +1139,7 @@
             field_userptr(this->Fields[findex-2]));
         if ( lbl )
           {
-          this->CMakeInstance->GetCacheManager()->RemoveCacheEntry(lbl->GetValue());
+          this->CMakeInstance->GetCacheManager()->RemoveCacheEntry(lbl->GetValue(), true);
 
           std::string nextVal;
           if (nextCur)
diff --exclude=CVS -Nur CMake.orig/Source/CursesDialog/cmCursesMainForm.h CMake/Source/CursesDialog/cmCursesMainForm.h
--- CMake.orig/Source/CursesDialog/cmCursesMainForm.h	2006-03-16 10:44:55.000000000 -0500
+++ CMake/Source/CursesDialog/cmCursesMainForm.h	2008-08-20 01:35:22.000000000 -0400
@@ -3,7 +3,7 @@
   Program:   CMake - Cross-Platform Makefile Generator
   Module:    $RCSfile: cmCursesMainForm.h,v $
   Language:  C++
-  Date:      $Date: 2006-03-16 15:44:55 $
+  Date:      $Date: 2006/03/16 15:44:55 $
   Version:   $Revision: 1.24 $
 
   Copyright (c) 2002 Kitware, Inc., Insight Consortium.  All rights reserved.
diff --exclude=CVS -Nur CMake.orig/Source/FLTKDialog/FLTKPropertyItemRow.cxx CMake/Source/FLTKDialog/FLTKPropertyItemRow.cxx
--- CMake.orig/Source/FLTKDialog/FLTKPropertyItemRow.cxx	2007-08-21 16:21:09.000000000 -0400
+++ CMake/Source/FLTKDialog/FLTKPropertyItemRow.cxx	2008-08-20 01:36:25.000000000 -0400
@@ -3,7 +3,7 @@
   Program:   Insight Segmentation & Registration Toolkit
   Module:    $RCSfile: FLTKPropertyItemRow.cxx,v $
   Language:  C++
-  Date:      $Date: 2007-08-21 20:21:09 $
+  Date:      $Date: 2007/08/21 20:21:09 $
   Version:   $Revision: 1.20 $
 
   Copyright (c) 2002 Insight Consortium. All rights reserved.
@@ -238,7 +238,7 @@
       if( answer == 1 )
       {
         // Remove the entry from the cache
-        m_CMakeSetup->GetCMakeInstance()->GetCacheManager()->RemoveCacheEntry(propertyName);
+        m_CMakeSetup->GetCMakeInstance()->GetCacheManager()->RemoveCacheEntry(propertyName, true);
           // Get the parent: Fl_Tile that manages the whole row in the GUI
         Fl_Group * parentGroup      = dynamic_cast<Fl_Group *>(button->parent());
         // Get the grandParent: Fl_Pack with the property list
diff --exclude=CVS -Nur CMake.orig/Source/FLTKDialog/FLTKPropertyList.cxx CMake/Source/FLTKDialog/FLTKPropertyList.cxx
--- CMake.orig/Source/FLTKDialog/FLTKPropertyList.cxx	2007-08-21 16:21:09.000000000 -0400
+++ CMake/Source/FLTKDialog/FLTKPropertyList.cxx	2008-08-20 01:36:25.000000000 -0400
@@ -3,7 +3,7 @@
   Program:   Insight Segmentation & Registration Toolkit
   Module:    $RCSfile: FLTKPropertyList.cxx,v $
   Language:  C++
-  Date:      $Date: 2007-08-21 20:21:09 $
+  Date:      $Date: 2007/08/21 20:21:09 $
   Version:   $Revision: 1.10 $
 
   Copyright (c) 2002 Insight Consortium. All rights reserved.
@@ -139,7 +139,7 @@
   for(int i =0; i < c; ++i)
     {
     PropertyItem* pItem = (PropertyItem*) GetItemDataPtr(0);
-//    cmCacheManager::GetInstance()->RemoveCacheEntry(pItem->m_propName.c_str());
+//    cmCacheManager::GetInstance()->RemoveCacheEntry(pItem->m_propName.c_str(), true);
     m_PropertyItems.erase(pItem);
     delete pItem;
     }
diff --exclude=CVS -Nur CMake.orig/Source/MFCDialog/PropertyList.cpp CMake/Source/MFCDialog/PropertyList.cpp
--- CMake.orig/Source/MFCDialog/PropertyList.cpp	2007-03-05 09:51:13.000000000 -0500
+++ CMake/Source/MFCDialog/PropertyList.cpp	2008-08-20 01:36:58.000000000 -0400
@@ -729,7 +729,7 @@
     return;
     }
   CPropertyItem* pItem = (CPropertyItem*) GetItemDataPtr(m_curSel);
-  m_CMakeSetupDialog->GetCMakeInstance()->GetCacheManager()->RemoveCacheEntry(pItem->m_propName);
+  m_CMakeSetupDialog->GetCMakeInstance()->GetCacheManager()->RemoveCacheEntry(pItem->m_propName, true);
   m_PropertyItems.erase(pItem);
   delete pItem; 
   this->DeleteString(m_curSel);
diff --exclude=CVS -Nur CMake.orig/Source/QtDialog/QCMake.cxx CMake/Source/QtDialog/QCMake.cxx
--- CMake.orig/Source/QtDialog/QCMake.cxx	2008-05-15 19:21:01.000000000 -0400
+++ CMake/Source/QtDialog/QCMake.cxx	2008-08-20 01:37:08.000000000 -0400
@@ -209,7 +209,7 @@
   // remove some properites
   foreach(QString s, toremove)
     {
-    cachem->RemoveCacheEntry(s.toAscii().data());
+    cachem->RemoveCacheEntry(s.toAscii().data(), true);
     }
   
   // add some new properites
diff --exclude=CVS -Nur CMake.orig/Source/WXDialog/PropertyList.cpp CMake/Source/WXDialog/PropertyList.cpp
--- CMake.orig/Source/WXDialog/PropertyList.cpp	2005-06-30 15:54:14.000000000 -0400
+++ CMake/Source/WXDialog/PropertyList.cpp	2008-08-20 01:37:30.000000000 -0400
@@ -3,7 +3,7 @@
   Program:   WXDialog - wxWidgets X-platform GUI Front-End for CMake
   Module:    $RCSfile: PropertyList.cpp,v $
   Language:  C++
-  Date:      $Date: 2005-06-30 19:54:14 $
+  Date:      $Date: 2005/06/30 19:54:14 $
   Version:   $Revision: 1.1 $
 
   Author:    Jorgen Bodde
@@ -486,7 +486,7 @@
     return;
     }
   wxPropertyItem* pItem = (wxPropertyItem*) GetItemDataPtr(m_curSel);
-  m_CMakeSetupDialog->GetCMakeInstance()->GetCacheManager()->RemoveCacheEntry(pItem->m_propName);
+  m_CMakeSetupDialog->GetCMakeInstance()->GetCacheManager()->RemoveCacheEntry(pItem->m_propName, true);
   m_PropertyItems.erase(pItem);
   delete pItem; 
   this->DeleteString(m_curSel);
diff --exclude=CVS -Nur CMake.orig/Tests/CMakeLists.txt CMake/Tests/CMakeLists.txt
--- CMake.orig/Tests/CMakeLists.txt	2008-08-19 11:43:57.000000000 -0400
+++ CMake/Tests/CMakeLists.txt	2008-08-22 00:11:29.000000000 -0400
@@ -94,6 +94,7 @@
   ADD_TEST_MACRO(SourceGroups SourceGroups)
   ADD_TEST_MACRO(Preprocess Preprocess)
   ADD_TEST_MACRO(ExportImport ExportImport)
+  ADD_TEST_MACRO(Unset Unset)
 
 
   # If we are running right now with a UnixMakefiles based generator,
diff --exclude=CVS -Nur CMake.orig/Tests/Unset/CMakeLists.txt CMake/Tests/Unset/CMakeLists.txt
--- CMake.orig/Tests/Unset/CMakeLists.txt	1969-12-31 19:00:00.000000000 -0500
+++ CMake/Tests/Unset/CMakeLists.txt	2008-08-22 00:14:40.000000000 -0400
@@ -0,0 +1,40 @@
+project(Unset)
+
+# Local variable
+set(x 42)
+if(NOT x EQUAL 42)
+    message(FATAL_ERROR "x!=42")
+endif(NOT x EQUAL 42)
+
+if(NOT DEFINED x)
+    message(FATAL_ERROR "x should be defined!")
+endif(NOT DEFINED x)
+
+unset(x)
+if(DEFINED x)
+    message(FATAL_ERROR "x should be undefined now!")
+endif(DEFINED x)
+
+# Local variable test unset via set()
+set(x 43)
+if(NOT x EQUAL 43)
+    message(FATAL_ERROR "x!=43")
+endif(NOT x EQUAL 43)
+set(x)
+if(DEFINED x)
+    message(FATAL_ERROR "x should be undefined now!")
+endif(DEFINED x)
+
+# Cache variable
+set(BAR "test" CACHE STRING "documentation")
+if(NOT DEFINED BAR)
+    message(FATAL_ERROR "BAR not defined")
+endif(NOT DEFINED BAR)
+
+unset(BAR CACHE)
+if(DEFINED BAR)
+    message(FATAL_ERROR "BAR still defined")
+endif(DEFINED BAR)
+
+
+add_executable(Unset unset.cc)
diff --exclude=CVS -Nur CMake.orig/Tests/Unset/unset.cc CMake/Tests/Unset/unset.cc
--- CMake.orig/Tests/Unset/unset.cc	1969-12-31 19:00:00.000000000 -0500
+++ CMake/Tests/Unset/unset.cc	2008-08-20 01:08:04.000000000 -0400
@@ -0,0 +1,4 @@
+int main()
+{
+   return 0;
+}