Issue #24585: Enables build-to-build upgrades that preserve settings.

Rather than using Burn "Persisted" variables we now add registry keys for each added feature. These can be detected by the installer regardless of which version installed them, and we use this for Modify and Upgrade. In particular, Upgrades can't access the Persisted variables, but can find well-known registry keys.
There are also some changes to the bootstrap app to properly handle upgrades.
Finally, a few minor improvements to the Windows build to keep things tidier.

31 files changed, 402 insertions, 123 deletions

diff --git a/Tools/msi/build.bat b/Tools/msi/build.bat
index 1dc05c3..c135b63 100644
--- a/Tools/msi/build.bat
+++ b/Tools/msi/build.bat
@@ -8,10 +8,10 @@ set BUILDX64=
 set BUILDDOC=

 

 :CheckOpts

-if "%1" EQU "-h" goto Help

-if "%1" EQU "-x86" (set BUILDX86=1) && shift && goto CheckOpts

-if "%1" EQU "-x64" (set BUILDX64=1) && shift && goto CheckOpts

-if "%1" EQU "--doc" (set BUILDDOC=1) && shift && goto CheckOpts

+if "%~1" EQU "-h" goto Help

+if "%~1" EQU "-x86" (set BUILDX86=1) && shift && goto CheckOpts

+if "%~1" EQU "-x64" (set BUILDX64=1) && shift && goto CheckOpts

+if "%~1" EQU "--doc" (set BUILDDOC=1) && shift && goto CheckOpts

 

 if not defined BUILDX86 if not defined BUILDX64 (set BUILDX86=1) && (set BUILDX64=1)

 

diff --git a/Tools/msi/bundle/Default.thm b/Tools/msi/bundle/Default.thm
index d5e1969..0c79dd5 100644
--- a/Tools/msi/bundle/Default.thm
+++ b/Tools/msi/bundle/Default.thm
@@ -21,13 +21,24 @@
 
         <Text X="185" Y="50" Width="-11" Height="50" FontId="3" TabStop="yes">#(loc.InstallMessage)</Text>
 
-        <Button Name="InstallJustForMeButton" X="175" Y="101" Width="-11" Height="129" TabStop="yes" FontId="3" HexStyle="0xE">#(loc.InstallJustForMeButton)</Button>
+        <Button Name="InstallButton" X="175" Y="101" Width="-11" Height="129" TabStop="yes" FontId="3" HexStyle="0xE">#(loc.InstallButton)</Button>
         <Button Name="InstallCustomButton" X="175" Y="241" Width="-11" Height="59" TabStop="yes" FontId="3" HexStyle="0xE">#(loc.InstallCustomButton)</Button>
 
         <Checkbox Name="PrependPath" X="185" Y="-13" Width="-100" Height="20" TabStop="yes" FontId="3">#(loc.ShortPrependPathLabel)</Checkbox>
 
         <Button Name="InstallCancelButton" X="-11" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0">#(loc.CancelButton)</Button>
     </Page>
+    <Page Name="Upgrade">
+        <Text X="185" Y="11" Width="-11" Height="32" FontId="1" DisablePrefix="yes">#(loc.InstallUpgradeHeader)</Text>
+        <Image X="0" Y="0" Width="162" Height="352" ImageFile="SideBar.png"/>
+
+        <Text X="185" Y="50" Width="-11" Height="50" FontId="3" TabStop="yes">#(loc.InstallUpgradeMessage)</Text>
+
+        <Button Name="InstallUpgradeButton" X="175" Y="101" Width="-11" Height="129" TabStop="yes" FontId="3" HexStyle="0xE">#(loc.InstallUpgradeButton)</Button>
+        <Button Name="InstallUpgradeCustomButton" X="175" Y="241" Width="-11" Height="59" TabStop="yes" FontId="3" HexStyle="0xE">#(loc.InstallUpgradeCustomButton)</Button>
+
+        <Button Name="InstallCancelButton" X="-11" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0">#(loc.CancelButton)</Button>
+    </Page>
     <Page Name="SimpleInstall">
         <Text X="185" Y="11" Width="-11" Height="32" FontId="1" DisablePrefix="yes">#(loc.InstallHeader)</Text>
         <Image X="0" Y="0" Width="162" Height="352" ImageFile="SideBar.png"/>
diff --git a/Tools/msi/bundle/Default.wxl b/Tools/msi/bundle/Default.wxl
index 3ecb2fa..19ba7eb 100644
--- a/Tools/msi/bundle/Default.wxl
+++ b/Tools/msi/bundle/Default.wxl
@@ -21,6 +21,8 @@ Continue?</String>
   <String Id="InstallHeader">Install [WixBundleName]</String>
   <String Id="InstallMessage">Select Install Now to install Python with default settings, or choose Customize to enable or disable features.</String>
   <String Id="InstallVersion">Version [WixBundleVersion]</String>
+  <String Id="InstallUpgradeHeader">Upgrade to [WixBundleName]</String>
+  <String Id="InstallUpgradeMessage">Select Upgrade Now to keep your current settings, or choose Customize to enable or disable features.</String>
   <String Id="ConfirmCancelMessage">Are you sure you want to cancel?</String>
   <String Id="ExecuteUpgradeRelatedBundleMessage">Previous version</String>
   <String Id="HelpHeader">Setup Help</String>
@@ -40,8 +42,8 @@ Continue?</String>
     Logs to a specific file. By default, log files are created in %TEMP%.</String>
   <String Id="InstallLicenseLinkText">[WixBundleName] &lt;a href="#"&gt;license terms&lt;/a&gt;.</String>
   <String Id="InstallAcceptCheckbox">I &amp;agree to the license terms and conditions</String>
-  <String Id="InstallJustForMeButton">&amp;Install Now</String>
-  <String Id="InstallJustForMeButtonNote">[DefaultJustForMeTargetDir]
+  <String Id="InstallButton">&amp;Install Now</String>
+  <String Id="InstallButtonNote">[DefaultJustForMeTargetDir]
 
 Includes IDLE, pip and documentation
 Creates shortcuts and file associations</String>
@@ -49,6 +51,13 @@ Creates shortcuts and file associations</String>
   <String Id="InstallCustomButtonNote">Choose location and features</String>
   <String Id="InstallSimpleButton">&amp;Install</String>
   <String Id="InstallSimpleButtonNote">Uses setting preselected by your administrator</String>
+  <String Id="InstallUpgradeButton">&amp;Upgrade Now</String>
+  <String Id="InstallUpgradeButtonNote">[TargetDir]
+
+Replaces your existing installation without changing settings.
+Select Customize to review current options.</String>
+  <String Id="InstallUpgradeCustomButton">C&amp;ustomize installation</String>
+  <String Id="InstallUpgradeCustomButtonNote">Choose location and features</String>
   <String Id="Custom1Header">Optional Features</String>
   <String Id="Custom2Header">Advanced Options</String>
   <String Id="CustomLocationLabel">Customize install location</String>
@@ -107,4 +116,5 @@ Feel free to email &lt;a href="mailto:python-list@python.org"&gt;python-list@pyt
   <String Id="FailureHyperlinkLogText">One or more issues caused the setup to fail. Please fix the issues and then retry setup. For more information see the &lt;a href="#"&gt;log file&lt;/a&gt;.</String>
   <String Id="FailureRestartText">You must restart your computer to complete the rollback of the software.</String>
   <String Id="FailureRestartButton">&amp;Restart</String>
+  <String Id="FailureExistingInstall">Unable to install [WixBundleName] due to an existing install. Use Programs and Features to modify, repair or remove [WixBundleName].</String>
 </WixLocalization>
diff --git a/Tools/msi/bundle/bootstrap/PythonBootstrapperApplication.cpp b/Tools/msi/bundle/bootstrap/PythonBootstrapperApplication.cpp
index 585f66c..7283559 100644
--- a/Tools/msi/bundle/bootstrap/PythonBootstrapperApplication.cpp
+++ b/Tools/msi/bundle/bootstrap/PythonBootstrapperApplication.cpp
@@ -47,6 +47,7 @@ enum PAGE {
     PAGE_LOADING,
     PAGE_HELP,
     PAGE_INSTALL,
+    PAGE_UPGRADE,
     PAGE_SIMPLE_INSTALL,
     PAGE_CUSTOM1,
     PAGE_CUSTOM2,
@@ -63,6 +64,7 @@ static LPCWSTR PAGE_NAMES[] = {
     L"Loading",
     L"Help",
     L"Install",
+    L"Upgrade",
     L"SimpleInstall",
     L"Custom1",
     L"Custom2",
@@ -79,10 +81,11 @@ enum CONTROL_ID {
     ID_MINIMIZE_BUTTON,
 
     // Welcome page
-    ID_INSTALL_ALL_USERS_BUTTON,
-    ID_INSTALL_JUST_FOR_ME_BUTTON,
+    ID_INSTALL_BUTTON,
     ID_INSTALL_CUSTOM_BUTTON,
     ID_INSTALL_SIMPLE_BUTTON,
+    ID_INSTALL_UPGRADE_BUTTON,
+    ID_INSTALL_UPGRADE_CUSTOM_BUTTON,
     ID_INSTALL_CANCEL_BUTTON,
     
     // Customize Page
@@ -141,10 +144,11 @@ static THEME_ASSIGN_CONTROL_ID CONTROL_ID_NAMES[] = {
     { ID_CLOSE_BUTTON, L"CloseButton" },
     { ID_MINIMIZE_BUTTON, L"MinimizeButton" },
 
-    { ID_INSTALL_ALL_USERS_BUTTON, L"InstallAllUsersButton" },
-    { ID_INSTALL_JUST_FOR_ME_BUTTON, L"InstallJustForMeButton" },
+    { ID_INSTALL_BUTTON, L"InstallButton" },
     { ID_INSTALL_CUSTOM_BUTTON, L"InstallCustomButton" },
     { ID_INSTALL_SIMPLE_BUTTON, L"InstallSimpleButton" },
+    { ID_INSTALL_UPGRADE_BUTTON, L"InstallUpgradeButton" },
+    { ID_INSTALL_UPGRADE_CUSTOM_BUTTON, L"InstallUpgradeCustomButton" },
     { ID_INSTALL_CANCEL_BUTTON, L"InstallCancelButton" },
 
     { ID_TARGETDIR_EDITBOX, L"TargetDir" },
@@ -191,13 +195,35 @@ static THEME_ASSIGN_CONTROL_ID CONTROL_ID_NAMES[] = {
     { ID_FAILURE_CANCEL_BUTTON, L"FailureCancelButton" },
 };
 
+static struct { LPCWSTR regName; LPCWSTR variableName; } OPTIONAL_FEATURES[] = {
+    { L"core_d", L"Include_debug" },
+    { L"core_pdb", L"Include_symbols" },
+    { L"dev", L"Include_dev" },
+    { L"doc", L"Include_doc" },
+    { L"exe", L"Include_exe" },
+    { L"lib", L"Include_lib" },
+    { L"path", L"PrependPath" },
+    { L"pip", L"Include_pip" },
+    { L"tcltk", L"Include_tcltk" },
+    { L"test", L"Include_test" },
+    { L"tools", L"Include_tools" },
+    { L"Shortcuts", L"Shortcuts" },
+    // Include_launcher and AssociateFiles are handled separately and so do
+    // not need to be included in this list.
+    { nullptr, nullptr }
+};
+
+
+
 class PythonBootstrapperApplication : public CBalBaseBootstrapperApplication {
     void ShowPage(DWORD newPageId) {
         // Process each control for special handling in the new page.
         ProcessPageControls(ThemeGetPage(_theme, newPageId));
 
         // Enable disable controls per-page.
-        if (_pageIds[PAGE_INSTALL] == newPageId || _pageIds[PAGE_SIMPLE_INSTALL] == newPageId) {
+        if (_pageIds[PAGE_INSTALL] == newPageId ||
+            _pageIds[PAGE_SIMPLE_INSTALL] == newPageId ||
+            _pageIds[PAGE_UPGRADE] == newPageId) {
             InstallPage_Show();
         } else if (_pageIds[PAGE_CUSTOM1] == newPageId) {
             Custom1Page_Show();
@@ -222,7 +248,7 @@ class PythonBootstrapperApplication : public CBalBaseBootstrapperApplication {
         // On the install page set the focus to the install button or
         // the next enabled control if install is disabled
         if (_pageIds[PAGE_INSTALL] == newPageId) {
-            ThemeSetFocus(_theme, ID_INSTALL_ALL_USERS_BUTTON);
+            ThemeSetFocus(_theme, ID_INSTALL_BUTTON);
         } else if (_pageIds[PAGE_SIMPLE_INSTALL] == newPageId) {
             ThemeSetFocus(_theme, ID_INSTALL_SIMPLE_BUTTON);
         }
@@ -234,7 +260,7 @@ class PythonBootstrapperApplication : public CBalBaseBootstrapperApplication {
     void OnCommand(CONTROL_ID id) {
         LPWSTR defaultDir = nullptr;
         LPWSTR targetDir = nullptr;
-        LONGLONG elevated, crtInstalled;
+        LONGLONG elevated, crtInstalled, installAllUsers;
         BOOL checked;
         WCHAR wzPath[MAX_PATH] = { };
         BROWSEINFOW browseInfo = { };
@@ -247,87 +273,42 @@ class PythonBootstrapperApplication : public CBalBaseBootstrapperApplication {
             break;
 
         // Install commands
-        case ID_INSTALL_SIMPLE_BUTTON:
-            hr = BalGetStringVariable(L"TargetDir", &targetDir);
-            if (FAILED(hr) || !targetDir || !*targetDir) {
-                LONGLONG installAll;
-                if (SUCCEEDED(BalGetNumericVariable(L"InstallAllUsers", &installAll)) && installAll) {
-                    hr = BalGetStringVariable(L"DefaultAllUsersTargetDir", &defaultDir);
-                    BalExitOnFailure(hr, "Failed to get the default all users install directory");
-                } else {
-                    hr = BalGetStringVariable(L"DefaultJustForMeTargetDir", &defaultDir);
-                    BalExitOnFailure(hr, "Failed to get the default per-user install directory");
-                }
-
-                if (!defaultDir || !*defaultDir) {
-                    BalLogError(E_INVALIDARG, "Default install directory is blank");
-                }
-
-                hr = BalFormatString(defaultDir, &targetDir);
-                BalExitOnFailure1(hr, "Failed to format '%ls'", defaultDir);
-
-                hr = _engine->SetVariableString(L"TargetDir", targetDir);
-                ReleaseStr(targetDir);
-                BalExitOnFailure(hr, "Failed to set install target directory");
-            } else {
-                ReleaseStr(targetDir);
-            }
-
-            OnPlan(BOOTSTRAPPER_ACTION_INSTALL);
-            break;
-
-        case ID_INSTALL_ALL_USERS_BUTTON:
-            SavePageSettings();
-            
-            hr = _engine->SetVariableNumeric(L"InstallAllUsers", 1);
-            ExitOnFailure(hr, L"Failed to set install scope");
-
-            hr = _engine->SetVariableNumeric(L"CompileAll", 1);
-            ExitOnFailure(hr, L"Failed to set compile all setting");
-
-            hr = BalGetStringVariable(L"DefaultAllUsersTargetDir", &defaultDir);
-            BalExitOnFailure(hr, "Failed to get the default all users install directory");
-
-            if (!defaultDir || !*defaultDir) {
-                BalLogError(E_INVALIDARG, "Default install directory is blank");
-            }
-
-            hr = BalFormatString(defaultDir, &targetDir);
-            BalExitOnFailure1(hr, "Failed to format '%ls'", defaultDir);
-
-            hr = _engine->SetVariableString(L"TargetDir", targetDir);
-            ReleaseStr(targetDir);
-            BalExitOnFailure(hr, "Failed to set install target directory");
-
-            OnPlan(BOOTSTRAPPER_ACTION_INSTALL);
-            break;
-
-        case ID_INSTALL_JUST_FOR_ME_BUTTON:
+        case ID_INSTALL_SIMPLE_BUTTON: __fallthrough;
+        case ID_INSTALL_UPGRADE_BUTTON: __fallthrough;
+        case ID_INSTALL_BUTTON:
             SavePageSettings();
 
             if (!QueryElevateForCrtInstall()) {
                 break;
             }
 
-            hr = _engine->SetVariableNumeric(L"InstallAllUsers", 0);
-            ExitOnFailure(hr, L"Failed to set install scope");
+            hr = BalGetNumericVariable(L"InstallAllUsers", &installAllUsers);
+            ExitOnFailure(hr, L"Failed to get install scope");
 
-            hr = _engine->SetVariableNumeric(L"CompileAll", 0);
-            ExitOnFailure(hr, L"Failed to unset CompileAll");
+            hr = _engine->SetVariableNumeric(L"CompileAll", installAllUsers);
+            ExitOnFailure(hr, L"Failed to update CompileAll");
 
-            hr = BalGetStringVariable(L"DefaultJustForMeTargetDir", &defaultDir);
-            BalExitOnFailure(hr, "Failed to get the default per-user install directory");
+            hr = BalGetStringVariable(L"TargetDir", &targetDir);
+            if (FAILED(hr) || !targetDir || !targetDir[0]) {
+                ReleaseStr(targetDir);
 
-            if (!defaultDir || !*defaultDir) {
-                BalLogError(E_INVALIDARG, "Default install directory is blank");
-            }
+                hr = BalGetStringVariable(
+                    installAllUsers ? L"DefaultAllUsersTargetDir" : L"DefaultJustForMeTargetDir",
+                    &defaultDir
+                );
+                BalExitOnFailure(hr, "Failed to get the default install directory");
 
-            hr = BalFormatString(defaultDir, &targetDir);
-            BalExitOnFailure1(hr, "Failed to format '%ls'", defaultDir);
+                if (!defaultDir || !defaultDir[0]) {
+                    BalLogError(E_INVALIDARG, "Default install directory is blank");
+                }
 
-            hr = _engine->SetVariableString(L"TargetDir", targetDir);
+                hr = BalFormatString(defaultDir, &targetDir);
+                BalExitOnFailure1(hr, "Failed to format '%ls'", defaultDir);
+
+                hr = _engine->SetVariableString(L"TargetDir", targetDir);
+                BalExitOnFailure(hr, "Failed to set install target directory");
+            }
             ReleaseStr(targetDir);
-            BalExitOnFailure(hr, "Failed to set install target directory");
 
             OnPlan(BOOTSTRAPPER_ACTION_INSTALL);
             break;
@@ -342,6 +323,7 @@ class PythonBootstrapperApplication : public CBalBaseBootstrapperApplication {
             break;
 
         case ID_INSTALL_CUSTOM_BUTTON: __fallthrough;
+        case ID_INSTALL_UPGRADE_CUSTOM_BUTTON: __fallthrough;
         case ID_CUSTOM2_BACK_BUTTON:
             SavePageSettings();
             GoToPage(PAGE_CUSTOM1);
@@ -460,10 +442,11 @@ class PythonBootstrapperApplication : public CBalBaseBootstrapperApplication {
             elevated = 0;
         }
 
-        ThemeControlElevates(_theme, ID_INSTALL_ALL_USERS_BUTTON, !elevated);
 
-        if (SUCCEEDED(BalGetNumericVariable(L"InstallAllUsers", &installAll)) && installAll) {
-            ThemeControlElevates(_theme, ID_INSTALL_SIMPLE_BUTTON, !elevated);
+        if (SUCCEEDED(BalGetNumericVariable(L"InstallAllUsers", &installAll)) && installAll && !elevated) {
+            ThemeControlElevates(_theme, ID_INSTALL_BUTTON, TRUE);
+            ThemeControlElevates(_theme, ID_INSTALL_SIMPLE_BUTTON, TRUE);
+            ThemeControlElevates(_theme, ID_INSTALL_UPGRADE_BUTTON, TRUE);
         }
     }
 
@@ -667,7 +650,34 @@ public: // IBootstrapperApplication
 
         // Remember when our bundle would cause a downgrade.
         if (BOOTSTRAPPER_RELATED_OPERATION_DOWNGRADE == operation) {
-            _downgrading = TRUE;
+            _downgradingOtherVersion = TRUE;
+        } else if (BOOTSTRAPPER_RELATED_OPERATION_MAJOR_UPGRADE == operation) {
+            _upgradingOldVersion = TRUE;
+
+            // Assume we don't want the launcher or file associations, and if
+            // they have already been installed then loading the state will
+            // reactivate these settings.
+            _engine->SetVariableNumeric(L"Include_launcher", 0);
+            _engine->SetVariableNumeric(L"AssociateFiles", 0);
+            auto hr = LoadLauncherStateFromKey(_engine, HKEY_CURRENT_USER);
+            if (hr == S_FALSE) {
+                hr = LoadLauncherStateFromKey(_engine, HKEY_LOCAL_MACHINE);
+            }
+        } else if (BOOTSTRAPPER_RELATED_OPERATION_NONE == operation) {
+            if (_command.action == BOOTSTRAPPER_ACTION_INSTALL) {
+                LOC_STRING *pLocString = nullptr;
+                if (SUCCEEDED(LocGetString(_wixLoc, L"#(loc.FailureExistingInstall)", &pLocString)) && pLocString) {
+                    BalFormatString(pLocString->wzText, &_failedMessage);
+                } else {
+                    BalFormatString(L"Cannot install [WixBundleName] because it is already installed.", &_failedMessage);
+                }
+                BalLog(
+                    BOOTSTRAPPER_LOG_LEVEL_ERROR,
+                    "Related bundle %ls is preventing install",
+                    wzBundleId
+                );
+                SetState(PYBA_STATE_FAILED, E_WIXSTDBA_CONDITION_FAILED);
+            }
         }
 
         return CheckCanceled() ? IDCANCEL : IDOK;
@@ -1969,7 +1979,7 @@ private:
         BalExitOnFailure(hr, "Failed to update strings");
 
         // If we are going to apply a downgrade, bail.
-        if (_downgrading && BOOTSTRAPPER_ACTION_UNINSTALL < action) {
+        if (_downgradingOtherVersion && BOOTSTRAPPER_ACTION_UNINSTALL < action) {
             if (_suppressDowngradeFailure) {
                 BalLog(BOOTSTRAPPER_LOG_LEVEL_STANDARD, "A newer version of this product is installed but downgrade failure has been suppressed; continuing...");
             } else {
@@ -2354,7 +2364,9 @@ private:
                 if (_installPage == PAGE_LOADING) {
                     switch (_command.action) {
                     case BOOTSTRAPPER_ACTION_INSTALL:
-                        if (SUCCEEDED(BalGetNumericVariable(L"SimpleInstall", &simple)) && simple) {
+                        if (_upgradingOldVersion) {
+                            _installPage = PAGE_UPGRADE;
+                        } else if (SUCCEEDED(BalGetNumericVariable(L"SimpleInstall", &simple)) && simple) {
                             _installPage = PAGE_SIMPLE_INSTALL;
                         } else {
                             _installPage = PAGE_INSTALL;
@@ -2608,6 +2620,179 @@ private:
         }
     }
 
+    static bool IsTargetPlatformx64(__in IBootstrapperEngine* pEngine) {
+        WCHAR platform[8];
+        DWORD platformLen = 8;
+
+        if (FAILED(pEngine->GetVariableString(L"TargetPlatform", platform, &platformLen))) {
+            return S_FALSE;
+        }
+
+        return ::CompareStringW(LOCALE_NEUTRAL, 0, platform, -1, L"x64", -1) == CSTR_EQUAL;
+    }
+
+    static HRESULT LoadOptionalFeatureStatesFromKey(
+        __in IBootstrapperEngine* pEngine,
+        __in HKEY hkHive,
+        __in LPCWSTR subkey
+    ) {
+        HKEY hKey;
+        LRESULT res;
+
+        if (IsTargetPlatformx64(pEngine)) {
+            res = RegOpenKeyExW(hkHive, subkey, 0, KEY_READ | KEY_WOW64_64KEY, &hKey);
+        } else {
+            res = RegOpenKeyExW(hkHive, subkey, 0, KEY_READ | KEY_WOW64_32KEY, &hKey);
+        }
+        if (res == ERROR_FILE_NOT_FOUND) {
+            return S_FALSE;
+        }
+        if (res != ERROR_SUCCESS) {
+            return HRESULT_FROM_WIN32(res);
+        }
+
+        for (auto p = OPTIONAL_FEATURES; p->regName; ++p) {
+            res = RegQueryValueExW(hKey, p->regName, nullptr, nullptr, nullptr, nullptr);
+            if (res == ERROR_FILE_NOT_FOUND) {
+                pEngine->SetVariableNumeric(p->variableName, 0);
+            } else if (res == ERROR_SUCCESS) {
+                pEngine->SetVariableNumeric(p->variableName, 1);
+            } else {
+                RegCloseKey(hKey);
+                return HRESULT_FROM_WIN32(res);
+            }
+        }
+
+        RegCloseKey(hKey);
+        return S_OK;
+    }
+
+    static HRESULT LoadTargetDirFromKey(
+        __in IBootstrapperEngine* pEngine,
+        __in HKEY hkHive,
+        __in LPCWSTR subkey
+    ) {
+        HKEY hKey;
+        LRESULT res;
+        DWORD dataType;
+        BYTE buffer[1024];
+        DWORD bufferLen = sizeof(buffer);
+
+        if (IsTargetPlatformx64(pEngine)) {
+            res = RegOpenKeyExW(hkHive, subkey, 0, KEY_READ | KEY_WOW64_64KEY, &hKey);
+        } else {
+            res = RegOpenKeyExW(hkHive, subkey, 0, KEY_READ | KEY_WOW64_32KEY, &hKey);
+        }
+        if (res == ERROR_FILE_NOT_FOUND) {
+            return S_FALSE;
+        }
+        if (res != ERROR_SUCCESS) {
+            return HRESULT_FROM_WIN32(res);
+        }
+
+        res = RegQueryValueExW(hKey, nullptr, nullptr, &dataType, buffer, &bufferLen);
+        if (res == ERROR_SUCCESS && dataType == REG_SZ && bufferLen < sizeof(buffer)) {
+            pEngine->SetVariableString(L"TargetDir", reinterpret_cast<wchar_t*>(buffer));
+        }
+        RegCloseKey(hKey);
+        return HRESULT_FROM_WIN32(res);
+    }
+
+    static HRESULT LoadLauncherStateFromKey(
+        __in IBootstrapperEngine* pEngine,
+        __in HKEY hkHive
+    ) {
+        const LPCWSTR subkey = L"Software\\Python\\PyLauncher";
+        HKEY hKey;
+        LRESULT res;
+
+        if (IsTargetPlatformx64(pEngine)) {
+            res = RegOpenKeyExW(hkHive, subkey, 0, KEY_READ | KEY_WOW64_64KEY, &hKey);
+        } else {
+            res = RegOpenKeyExW(hkHive, subkey, 0, KEY_READ | KEY_WOW64_32KEY, &hKey);
+        }
+
+        if (res == ERROR_FILE_NOT_FOUND) {
+            return S_FALSE;
+        }
+        if (res != ERROR_SUCCESS) {
+            return HRESULT_FROM_WIN32(res);
+        }
+
+        res = RegQueryValueExW(hKey, nullptr, nullptr, nullptr, nullptr, nullptr);
+        if (res == ERROR_FILE_NOT_FOUND) {
+            pEngine->SetVariableNumeric(L"Include_launcher", 0);
+        } else if (res == ERROR_SUCCESS) {
+            pEngine->SetVariableNumeric(L"Include_launcher", 1);
+        }
+
+        res = RegQueryValueExW(hKey, L"AssociateFiles", nullptr, nullptr, nullptr, nullptr);
+        if (res == ERROR_FILE_NOT_FOUND) {
+            pEngine->SetVariableNumeric(L"AssociateFiles", 0);
+        } else if (res == ERROR_SUCCESS) {
+            pEngine->SetVariableNumeric(L"AssociateFiles", 1);
+        }
+
+        RegCloseKey(hKey);
+        return S_OK;
+    }
+
+    static void LoadOptionalFeatureStates(__in IBootstrapperEngine* pEngine) {
+        WCHAR subkeyFmt[256];
+        WCHAR subkey[256];
+        DWORD subkeyLen;
+        HRESULT hr;
+        HKEY hkHive;
+
+        // The launcher installation is separate from the Python install, so we
+        // check its state later. This also checks the file association option.
+
+        // Get the registry key from the bundle, to save having to duplicate it
+        // in multiple places.
+        subkeyLen = sizeof(subkeyFmt) / sizeof(subkeyFmt[0]);
+        hr = pEngine->GetVariableString(L"OptionalFeaturesRegistryKey", subkeyFmt, &subkeyLen);
+        BalExitOnFailure(hr, "Failed to locate registry key");
+        subkeyLen = sizeof(subkey) / sizeof(subkey[0]);
+        hr = pEngine->FormatString(subkeyFmt, subkey, &subkeyLen);
+        BalExitOnFailure1(hr, "Failed to format %ls", subkeyFmt);
+
+        // Check the current user's registry for existing features
+        hkHive = HKEY_CURRENT_USER;
+        hr = LoadOptionalFeatureStatesFromKey(pEngine, hkHive, subkey);
+        BalExitOnFailure1(hr, "Failed to read from HKCU\\%ls", subkey);
+        if (hr == S_FALSE) {
+            // Now check the local machine registry
+            hkHive = HKEY_LOCAL_MACHINE;
+            hr = LoadOptionalFeatureStatesFromKey(pEngine, hkHive, subkey);
+            BalExitOnFailure1(hr, "Failed to read from HKLM\\%ls", subkey);
+            if (hr == S_OK) {
+                // Found a system-wide install, so enable these settings.
+                pEngine->SetVariableNumeric(L"InstallAllUsers", 1);
+                pEngine->SetVariableNumeric(L"CompileAll", 1);
+            }
+        }
+
+        if (hr == S_OK) {
+            // Cannot change InstallAllUsersState when upgrading. While there's
+            // no good reason to not allow installing a per-user and an all-user
+            // version simultaneously, Burn can't handle the state management
+            // and will need to uninstall the old one. 
+            pEngine->SetVariableString(L"InstallAllUsersState", L"disable");
+
+            // Get the previous install directory. This can be changed by the
+            // user.
+            subkeyLen = sizeof(subkeyFmt) / sizeof(subkeyFmt[0]);
+            hr = pEngine->GetVariableString(L"TargetDirRegistryKey", subkeyFmt, &subkeyLen);
+            BalExitOnFailure(hr, "Failed to locate registry key");
+            subkeyLen = sizeof(subkey) / sizeof(subkey[0]);
+            hr = pEngine->FormatString(subkeyFmt, subkey, &subkeyLen);
+            BalExitOnFailure1(hr, "Failed to format %ls", subkeyFmt);
+            LoadTargetDirFromKey(pEngine, hkHive, subkey);
+        }
+
+    LExit:
+        return;
+    }
 
 public:
     //
@@ -2667,7 +2852,8 @@ public:
         _installPage = PAGE_LOADING;
         _hrFinal = hrHostInitialization;
 
-        _downgrading = FALSE;
+        _downgradingOtherVersion = FALSE;
+        _upgradingOldVersion = FALSE;
         _restartResult = BOOTSTRAPPER_APPLY_RESTART_NONE;
         _restartRequired = FALSE;
         _allowRestart = FALSE;
@@ -2690,6 +2876,8 @@ public:
 
         _hBAFModule = nullptr;
         _baFunction = nullptr;
+
+        LoadOptionalFeatureStates(pEngine);
     }
 
 
@@ -2748,7 +2936,8 @@ private:
     DWORD _calculatedCacheProgress;
     DWORD _calculatedExecuteProgress;
 
-    BOOL _downgrading;
+    BOOL _downgradingOtherVersion;
+    BOOL _upgradingOldVersion;
     BOOTSTRAPPER_APPLY_RESTART _restartResult;
     BOOL _restartRequired;
     BOOL _allowRestart;
diff --git a/Tools/msi/bundle/bootstrap/pythonba.vcxproj b/Tools/msi/bundle/bootstrap/pythonba.vcxproj
index 5d8337c..be12957 100644
--- a/Tools/msi/bundle/bootstrap/pythonba.vcxproj
+++ b/Tools/msi/bundle/bootstrap/pythonba.vcxproj
@@ -31,7 +31,7 @@
   <PropertyGroup Label="Configuration">
     <ConfigurationType>DynamicLibrary</ConfigurationType>
     <CharacterSet>Unicode</CharacterSet>
-    <IntDir>$(ProjectDir)..\..\obj\$(Configuration)_Bootstrap\</IntDir>
+    <IntDir>$(PySourcePath)PCBuild\obj\$(Configuration)_$(Platform)_Setup\Bootstrap\</IntDir>
     <OutDir>$(IntDir)</OutDir>
   </PropertyGroup>
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.props" />
diff --git a/Tools/msi/bundle/bundle.wxs b/Tools/msi/bundle/bundle.wxs
index 76e87ab..678dac4 100644
--- a/Tools/msi/bundle/bundle.wxs
+++ b/Tools/msi/bundle/bundle.wxs
@@ -23,14 +23,18 @@
     <Variable Name="ShortVersion" Value="$(var.MajorVersionNumber).$(var.MinorVersionNumber)" />
     <Variable Name="ShortVersionNoDot" Value="$(var.MajorVersionNumber)$(var.MinorVersionNumber)" />
 
-    <Variable Name="InstallAllUsers" Value="0" Persisted="yes" bal:Overridable="yes" />
-    <Variable Name="TargetDir" Value="" Persisted="yes" bal:Overridable="yes" />
+    <Variable Name="InstallAllUsers" Value="0" bal:Overridable="yes" />
+    <Variable Name="TargetDir" Value="" bal:Overridable="yes" />
     <?if $(var.Platform)~="x64" ?>
     <Variable Name="DefaultAllUsersTargetDir" Value="[ProgramFiles64Folder]Python [ShortVersion]" bal:Overridable="yes" />
+    <Variable Name="TargetPlatform" Value="x64" />
     <?else ?>
     <Variable Name="DefaultAllUsersTargetDir" Value="[ProgramFilesFolder]Python [ShortVersion]" bal:Overridable="yes" />
+    <Variable Name="TargetPlatform" Value="x86" />
     <?endif ?>
     <Variable Name="DefaultJustForMeTargetDir" Value="[LocalAppDataFolder]Programs\Python\Python[ShortVersionNoDot]$(var.Suffix32)" bal:Overridable="yes" />
+    <Variable Name="OptionalFeaturesRegistryKey" Value="Software\$(var.TestPrefix)Python\PythonCore\[ShortVersion]$(var.Suffix32)\InstalledFeatures" />
+    <Variable Name="TargetDirRegistryKey" Value="Software\$(var.TestPrefix)Python\PythonCore\[ShortVersion]$(var.Suffix32)\InstallPath" />
     
     <!--
     An empty string will use the other defaults based on InstallAllUsers
@@ -44,23 +48,23 @@
     <Variable Name="TargetDirState" Value="enabled" />
     <Variable Name="CustomBrowseButtonState" Value="enabled" />
 
-    <Variable Name="Include_core" Value="1" Persisted="yes" />
-    <Variable Name="Include_exe" Value="1" Persisted="yes" bal:Overridable="yes" />
-    <Variable Name="Include_dev" Value="1" Persisted="yes" bal:Overridable="yes" />
-    <Variable Name="Include_lib" Value="1" Persisted="yes" bal:Overridable="yes" />
-    <Variable Name="Include_test" Value="1" Persisted="yes" bal:Overridable="yes" />
-    <Variable Name="Include_doc" Value="1" Persisted="yes" bal:Overridable="yes" />
-    <Variable Name="Include_tools" Value="1" Persisted="yes" bal:Overridable="yes" />
-    <Variable Name="Include_tcltk" Value="1" Persisted="yes" bal:Overridable="yes" />
-    <Variable Name="Include_pip" Value="1" Persisted="yes" bal:Overridable="yes" />
-    <Variable Name="Include_launcher" Value="1" Persisted="yes" bal:Overridable="yes" />
-    <Variable Name="Include_symbols" Value="0" Persisted="yes" bal:Overridable="yes" />
-    <Variable Name="Include_debug" Value="0" Persisted="yes" bal:Overridable="yes" />
+    <Variable Name="Include_core" Value="1" />
+    <Variable Name="Include_exe" Value="1" bal:Overridable="yes" />
+    <Variable Name="Include_dev" Value="1" bal:Overridable="yes" />
+    <Variable Name="Include_lib" Value="1" bal:Overridable="yes" />
+    <Variable Name="Include_test" Value="1" bal:Overridable="yes" />
+    <Variable Name="Include_doc" Value="1" bal:Overridable="yes" />
+    <Variable Name="Include_tools" Value="1" bal:Overridable="yes" />
+    <Variable Name="Include_tcltk" Value="1" bal:Overridable="yes" />
+    <Variable Name="Include_pip" Value="1" bal:Overridable="yes" />
+    <Variable Name="Include_launcher" Value="1" bal:Overridable="yes" />
+    <Variable Name="Include_symbols" Value="0" bal:Overridable="yes" />
+    <Variable Name="Include_debug" Value="0" bal:Overridable="yes" />
     
-    <Variable Name="AssociateFiles" Value="1" Persisted="yes" bal:Overridable="yes" />
-    <Variable Name="Shortcuts" Value="1" Persisted="yes" bal:Overridable="yes" />
-    <Variable Name="PrependPath" Value="0" Persisted="yes" bal:Overridable="yes" />
-    <Variable Name="CompileAll" Value="0" Persisted="yes" bal:Overridable="yes" />
+    <Variable Name="AssociateFiles" Value="1" bal:Overridable="yes" />
+    <Variable Name="Shortcuts" Value="1" bal:Overridable="yes" />
+    <Variable Name="PrependPath" Value="0" bal:Overridable="yes" />
+    <Variable Name="CompileAll" Value="0" bal:Overridable="yes" />
     
     <Variable Name="SimpleInstall" Value="0" bal:Overridable="yes" />
     
diff --git a/Tools/msi/bundle/packagegroups/core.wxs b/Tools/msi/bundle/packagegroups/core.wxs
index 9df6b79..a789585 100644
--- a/Tools/msi/bundle/packagegroups/core.wxs
+++ b/Tools/msi/bundle/packagegroups/core.wxs
@@ -9,6 +9,7 @@
                         ForcePerMachine="yes"
                         InstallCondition="InstallAllUsers and (Include_core or Include_exe or Include_launcher or Include_pip)">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
             <MsiPackage Id="core_AllUsers_pdb"
                         SourceFile="core_pdb.msi"
@@ -17,6 +18,7 @@
                         ForcePerMachine="yes"
                         InstallCondition="InstallAllUsers and (Include_core or Include_exe or Include_launcher or Include_pip) and Include_symbols">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
             <MsiPackage Id="core_AllUsers_d"
                         SourceFile="core_d.msi"
@@ -25,6 +27,7 @@
                         ForcePerMachine="yes"
                         InstallCondition="InstallAllUsers and (Include_core or Include_exe or Include_launcher or Include_pip) and Include_debug">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
 
             <MsiPackage Id="core_JustForMe"
@@ -34,6 +37,7 @@
                         ForcePerMachine="no"
                         InstallCondition="not InstallAllUsers and (Include_core or Include_exe or Include_launcher or Include_pip)">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
             <MsiPackage Id="core_JustForMe_pdb"
                         SourceFile="core_pdb.msi"
@@ -42,6 +46,7 @@
                         ForcePerMachine="no"
                         InstallCondition="not InstallAllUsers and (Include_core or Include_exe or Include_launcher or Include_pip) and Include_symbols">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
             <MsiPackage Id="core_JustForMe_d"
                         SourceFile="core_d.msi"
@@ -50,6 +55,7 @@
                         ForcePerMachine="no"
                         InstallCondition="not InstallAllUsers and (Include_core or Include_exe or Include_launcher or Include_pip) and Include_debug">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
         </PackageGroup>
     </Fragment>
diff --git a/Tools/msi/bundle/packagegroups/dev.wxs b/Tools/msi/bundle/packagegroups/dev.wxs
index f2ea29b..f7f5025 100644
--- a/Tools/msi/bundle/packagegroups/dev.wxs
+++ b/Tools/msi/bundle/packagegroups/dev.wxs
@@ -9,6 +9,7 @@
                         ForcePerMachine="yes"
                         InstallCondition="InstallAllUsers and Include_dev">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
             <MsiPackage Id="dev_AllUsers_d"
                         SourceFile="dev_d.msi"
@@ -17,6 +18,7 @@
                         ForcePerMachine="yes"
                         InstallCondition="InstallAllUsers and Include_dev and Include_debug">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
 
             <MsiPackage Id="dev_JustForMe"
@@ -26,6 +28,7 @@
                         ForcePerMachine="no"
                         InstallCondition="not InstallAllUsers and Include_dev">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
             <MsiPackage Id="dev_JustForMe_d"
                         SourceFile="dev_d.msi"
@@ -34,6 +37,7 @@
                         ForcePerMachine="no"
                         InstallCondition="not InstallAllUsers and Include_dev and Include_debug">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
         </PackageGroup>
     </Fragment>
diff --git a/Tools/msi/bundle/packagegroups/doc.wxs b/Tools/msi/bundle/packagegroups/doc.wxs
index 7843f44..2f11e27 100644
--- a/Tools/msi/bundle/packagegroups/doc.wxs
+++ b/Tools/msi/bundle/packagegroups/doc.wxs
@@ -10,6 +10,7 @@
                         ForcePerMachine="yes"
                         InstallCondition="InstallAllUsers and Include_doc">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
             
             <MsiPackage Id="doc_JustForMe"
@@ -20,6 +21,7 @@
                         ForcePerMachine="no"
                         InstallCondition="not InstallAllUsers and Include_doc">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
         </PackageGroup>
     </Fragment>
diff --git a/Tools/msi/bundle/packagegroups/exe.wxs b/Tools/msi/bundle/packagegroups/exe.wxs
index 50346d9..03d6f62 100644
--- a/Tools/msi/bundle/packagegroups/exe.wxs
+++ b/Tools/msi/bundle/packagegroups/exe.wxs
@@ -10,6 +10,7 @@
                         EnableFeatureSelection="yes"
                         InstallCondition="InstallAllUsers and (Include_exe or Include_launcher or Include_pip)">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
             <MsiPackage Id="exe_AllUsers_pdb"
                         SourceFile="exe_pdb.msi"
@@ -18,6 +19,7 @@
                         DownloadUrl="$(var.DownloadUrl)"
                         InstallCondition="InstallAllUsers and (Include_exe or Include_launcher or Include_pip) and Include_symbols">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
             <MsiPackage Id="exe_AllUsers_d"
                         SourceFile="exe_d.msi"
@@ -26,6 +28,7 @@
                         DownloadUrl="$(var.DownloadUrl)"
                         InstallCondition="InstallAllUsers and (Include_exe or Include_launcher or Include_pip) and Include_debug">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
             
             <MsiPackage Id="exe_JustForMe"
@@ -36,6 +39,7 @@
                         EnableFeatureSelection="yes"
                         InstallCondition="not InstallAllUsers and (Include_exe or Include_launcher or Include_pip)">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
             <MsiPackage Id="exe_JustForMe_pdb"
                         SourceFile="exe_pdb.msi"
@@ -44,6 +48,7 @@
                         DownloadUrl="$(var.DownloadUrl)"
                         InstallCondition="not InstallAllUsers and (Include_exe or Include_launcher or Include_pip) and Include_symbols">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
             <MsiPackage Id="exe_JustForMe_d"
                         SourceFile="exe_d.msi"
@@ -52,6 +57,7 @@
                         DownloadUrl="$(var.DownloadUrl)"
                         InstallCondition="not InstallAllUsers and (Include_exe or Include_launcher or Include_pip) and Include_debug">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
         </PackageGroup>
     </Fragment>
diff --git a/Tools/msi/bundle/packagegroups/lib.wxs b/Tools/msi/bundle/packagegroups/lib.wxs
index 47a97f1..f7c57c8 100644
--- a/Tools/msi/bundle/packagegroups/lib.wxs
+++ b/Tools/msi/bundle/packagegroups/lib.wxs
@@ -9,6 +9,7 @@
                         ForcePerMachine="yes"
                         InstallCondition="InstallAllUsers and Include_lib">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
             <MsiPackage Id="lib_AllUsers_pdb"
                         SourceFile="lib_pdb.msi"
@@ -17,6 +18,7 @@
                         ForcePerMachine="yes"
                         InstallCondition="InstallAllUsers and Include_lib and Include_symbols">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
             <MsiPackage Id="lib_AllUsers_d"
                         SourceFile="lib_d.msi"
@@ -25,6 +27,7 @@
                         ForcePerMachine="yes"
                         InstallCondition="InstallAllUsers and Include_lib and Include_debug">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
 
             <MsiPackage Id="lib_JustForMe"
@@ -34,6 +37,7 @@
                         ForcePerMachine="no"
                         InstallCondition="not InstallAllUsers and Include_lib">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
             <MsiPackage Id="lib_JustForMe_pdb"
                         SourceFile="lib_pdb.msi"
@@ -42,6 +46,7 @@
                         ForcePerMachine="no"
                         InstallCondition="not InstallAllUsers and Include_lib and Include_symbols">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
             <MsiPackage Id="lib_JustForMe_d"
                         SourceFile="lib_d.msi"
@@ -50,6 +55,7 @@
                         ForcePerMachine="no"
                         InstallCondition="not InstallAllUsers and Include_lib and Include_debug">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
         </PackageGroup>
     </Fragment>
diff --git a/Tools/msi/bundle/packagegroups/postinstall.wxs b/Tools/msi/bundle/packagegroups/postinstall.wxs
index 35978cc..4c50001 100644
--- a/Tools/msi/bundle/packagegroups/postinstall.wxs
+++ b/Tools/msi/bundle/packagegroups/postinstall.wxs
@@ -9,6 +9,7 @@
                         ForcePerMachine="yes"
                         InstallCondition="InstallAllUsers and Include_pip">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
             <MsiPackage Id="pip_JustForMe"
                         SourceFile="pip.msi"
@@ -17,6 +18,7 @@
                         ForcePerMachine="no"
                         InstallCondition="not InstallAllUsers and Include_pip">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
             
             <MsiPackage Id="path_AllUsers"
@@ -26,6 +28,7 @@
                         ForcePerMachine="yes"
                         InstallCondition="InstallAllUsers and PrependPath">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
             <MsiPackage Id="path_JustForMe"
                         SourceFile="path.msi"
@@ -34,6 +37,7 @@
                         ForcePerMachine="no"
                         InstallCondition="not InstallAllUsers and PrependPath">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
             
             <?define CompileAllCommand=-$(var.ShortVersion)$(var.Suffix32) -E -s -Wi "[TargetDir]\Lib\compileall.py" -f -x "bad_coding|badsyntax|site-packages|py2_|lib2to3\\tests|venv\\scripts" "[TargetDir]\Lib"?>
diff --git a/Tools/msi/bundle/packagegroups/tcltk.wxs b/Tools/msi/bundle/packagegroups/tcltk.wxs
index e0e3958..92f41cb 100644
--- a/Tools/msi/bundle/packagegroups/tcltk.wxs
+++ b/Tools/msi/bundle/packagegroups/tcltk.wxs
@@ -10,6 +10,7 @@
                         EnableFeatureSelection="yes"
                         InstallCondition="InstallAllUsers and Include_tcltk">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
             <MsiPackage Id="tcltk_AllUsers_pdb"
                         SourceFile="tcltk_pdb.msi"
@@ -19,6 +20,7 @@
                         EnableFeatureSelection="yes"
                         InstallCondition="InstallAllUsers and Include_tcltk and Include_symbols">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
             <MsiPackage Id="tcltk_AllUsers_d"
                         SourceFile="tcltk_d.msi"
@@ -28,6 +30,7 @@
                         EnableFeatureSelection="yes"
                         InstallCondition="InstallAllUsers and Include_tcltk and Include_debug">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
 
             <MsiPackage Id="tcltk_JustForMe"
@@ -38,6 +41,7 @@
                         EnableFeatureSelection="yes"
                         InstallCondition="not InstallAllUsers and Include_tcltk">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
             <MsiPackage Id="tcltk_JustForMe_pdb"
                         SourceFile="tcltk_pdb.msi"
@@ -47,6 +51,7 @@
                         EnableFeatureSelection="yes"
                         InstallCondition="not InstallAllUsers and Include_tcltk and Include_symbols">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
             <MsiPackage Id="tcltk_JustForMe_d"
                         SourceFile="tcltk_d.msi"
@@ -56,6 +61,7 @@
                         EnableFeatureSelection="yes"
                         InstallCondition="not InstallAllUsers and Include_tcltk and Include_debug">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
         </PackageGroup>
     </Fragment>
diff --git a/Tools/msi/bundle/packagegroups/test.wxs b/Tools/msi/bundle/packagegroups/test.wxs
index b64e8ff..b3e0f3e 100644
--- a/Tools/msi/bundle/packagegroups/test.wxs
+++ b/Tools/msi/bundle/packagegroups/test.wxs
@@ -9,6 +9,7 @@
                         ForcePerMachine="yes"
                         InstallCondition="InstallAllUsers and Include_test">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
             <MsiPackage Id="test_AllUsers_pdb"
                         SourceFile="test_pdb.msi"
@@ -17,6 +18,7 @@
                         ForcePerMachine="yes"
                         InstallCondition="InstallAllUsers and Include_test and Include_symbols">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
             <MsiPackage Id="test_AllUsers_d"
                         SourceFile="test_d.msi"
@@ -25,6 +27,7 @@
                         ForcePerMachine="yes"
                         InstallCondition="InstallAllUsers and Include_test and Include_debug">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
 
             <MsiPackage Id="test_JustForMe"
@@ -34,6 +37,7 @@
                         ForcePerMachine="no"
                         InstallCondition="not InstallAllUsers and Include_test">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
             <MsiPackage Id="test_JustForMe_pdb"
                         SourceFile="test_pdb.msi"
@@ -42,6 +46,7 @@
                         ForcePerMachine="no"
                         InstallCondition="not InstallAllUsers and Include_test and Include_symbols">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
             <MsiPackage Id="test_JustForMe_d"
                         SourceFile="test_d.msi"
@@ -50,6 +55,7 @@
                         ForcePerMachine="no"
                         InstallCondition="not InstallAllUsers and Include_test and Include_debug">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
         </PackageGroup>
     </Fragment>
diff --git a/Tools/msi/bundle/packagegroups/tools.wxs b/Tools/msi/bundle/packagegroups/tools.wxs
index 06af5b5..c92f27b 100644
--- a/Tools/msi/bundle/packagegroups/tools.wxs
+++ b/Tools/msi/bundle/packagegroups/tools.wxs
@@ -9,6 +9,7 @@
                         ForcePerMachine="yes"
                         InstallCondition="InstallAllUsers and Include_tools">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
             
             <MsiPackage Id="tools_JustForMe"
@@ -18,6 +19,7 @@
                         ForcePerMachine="no"
                         InstallCondition="not InstallAllUsers and Include_tools">
                 <MsiProperty Name="TARGETDIR" Value="[TargetDir]" />
+                <MsiProperty Name="OPTIONALFEATURESREGISTRYKEY" Value="[OptionalFeaturesRegistryKey]" />
             </MsiPackage>
         </PackageGroup>
     </Fragment>
diff --git a/Tools/msi/common.wxs b/Tools/msi/common.wxs
index 7529aab..cc39540 100644
--- a/Tools/msi/common.wxs
+++ b/Tools/msi/common.wxs
@@ -5,6 +5,15 @@
     </Fragment>
     
     <Fragment>
+        <Component Id="OptionalFeature" Guid="*" Directory="InstallDirectory">
+            <Condition>OPTIONALFEATURESREGISTRYKEY</Condition>
+            <RegistryKey Root="HKMU" Key="[OPTIONALFEATURESREGISTRYKEY]">
+                <RegistryValue Type="string" Name="$(var.OptionalFeatureName)" Value="$(var.Version)" KeyPath="yes" />
+            </RegistryKey>
+        </Component>
+    </Fragment>
+    
+    <Fragment>
         <Property Id="UpgradeTable" Value="1" />
         
         <Upgrade Id="$(var.UpgradeCode)">
diff --git a/Tools/msi/core/core_d.wxs b/Tools/msi/core/core_d.wxs
index 8422117..bb35f99 100644
--- a/Tools/msi/core/core_d.wxs
+++ b/Tools/msi/core/core_d.wxs
@@ -8,6 +8,7 @@
         
         <Feature Id="DebugBinaries" AllowAdvertise="no" Title="!(loc.Title_d)" Description="!(loc.Description_d)">
             <ComponentGroupRef Id="core_dll_d" />
+            <ComponentRef Id="OptionalFeature" />
         </Feature>
     </Product>
 </Wix>
diff --git a/Tools/msi/core/core_pdb.wxs b/Tools/msi/core/core_pdb.wxs
index c9a558d..ba72d95 100644
--- a/Tools/msi/core/core_pdb.wxs
+++ b/Tools/msi/core/core_pdb.wxs
@@ -8,6 +8,7 @@
         
         <Feature Id="Symbols" AllowAdvertise="no" Title="!(loc.TitlePdb)" Description="!(loc.DescriptionPdb)">
             <ComponentGroupRef Id="core_symbols" />
+            <ComponentRef Id="OptionalFeature" />
         </Feature>
     </Product>
 </Wix>
diff --git a/Tools/msi/dev/dev.wxs b/Tools/msi/dev/dev.wxs
index f8af9aa..a09e139 100644
--- a/Tools/msi/dev/dev.wxs
+++ b/Tools/msi/dev/dev.wxs
@@ -13,6 +13,7 @@
 <?ifdef IncludeMinGWLib ?>
             <ComponentGroupRef Id="dev_mingw" />
 <?endif ?>
+            <ComponentRef Id="OptionalFeature" />
         </Feature>
     </Product>
 </Wix>
diff --git a/Tools/msi/doc/doc.wxs b/Tools/msi/doc/doc.wxs
index 22b0213..bbe30a1 100644
--- a/Tools/msi/doc/doc.wxs
+++ b/Tools/msi/doc/doc.wxs
@@ -9,13 +9,16 @@
         
         <Feature Id="DefaultFeature" AllowAdvertise="no" Title="!(loc.Title)" Description="!(loc.Description)">
             <ComponentGroupRef Id="doc" Primary="yes" />
+            <ComponentRef Id="OptionalFeature" />
         </Feature>
         <Feature Id="Shortcuts" AllowAdvertise="no" Title="!(loc.Title)" Description="!(loc.Description)">
             <ComponentGroupRef Id="doc" />
             
             <?ifdef DocFilename ?>
             <Component Id="doc_shortcut" Directory="MenuDir" Guid="*">
-                <RegistryValue Root="HKMU" Key="[REGISTRYKEY]\DocShortcuts" Type="integer" Value="1" KeyPath="yes" />
+                <RegistryKey Root="HKMU" Key="[OPTIONALFEATURESREGISTRYKEY]">
+                    <RegistryValue Name="$(var.OptionalFeatureName)_shortcut" Type="string" Value="$(var.Version)" KeyPath="yes" />
+                </RegistryKey>
                 <Shortcut Id="python.chm"
                           Target="[#python.chm]"
                           Name="!(loc.ShortcutName)"
diff --git a/Tools/msi/exe/exe.wxs b/Tools/msi/exe/exe.wxs
index d8b05e0..dcbf646 100644
--- a/Tools/msi/exe/exe.wxs
+++ b/Tools/msi/exe/exe.wxs
@@ -11,6 +11,7 @@
             <ComponentGroupRef Id="exe_python" Primary="yes" />
             <ComponentGroupRef Id="exe_txt" />
             <ComponentGroupRef Id="exe_icons" />
+            <ComponentRef Id="OptionalFeature" />
         </Feature>
             
         <Feature Id="Shortcuts" AllowAdvertise="no" Title="!(loc.Title)" Description="!(loc.Description)">
@@ -23,6 +24,7 @@
                 <RemoveFolder Id="Remove_MenuDir" Directory="MenuDir" On="uninstall" />
                 <RegistryKey Root="HKMU" Key="[REGISTRYKEY]">
                     <RegistryValue Key="InstallPath\InstallGroup" Type="string" Value="!(loc.ProductName)" KeyPath="yes" />
+                    <RegistryValue Key="InstalledFeatures" Name="Shortcuts" Type="string" Value="$(var.Version)" />
                 </RegistryKey>
             </Component>
         </Feature>
diff --git a/Tools/msi/exe/exe_files.wxs b/Tools/msi/exe/exe_files.wxs
index 6422372..3b5fce4 100644
--- a/Tools/msi/exe/exe_files.wxs
+++ b/Tools/msi/exe/exe_files.wxs
@@ -23,6 +23,7 @@
                 
                 <RegistryKey Root="HKMU" Key="[REGISTRYKEY]">
                     <RegistryValue Key="InstallPath" Type="string" Value="[InstallDirectory]" KeyPath="no" />
+                    <RegistryValue Key="InstallPath" Name="ExecutablePath" Type="string" Value="[#python.exe]" KeyPath="no" />
                 </RegistryKey>
             </Component>
             <Component Id="pythonw.exe" Directory="InstallDirectory" Guid="$(var.PythonwExeComponentGuid)">
diff --git a/Tools/msi/launcher/launcher_files.wxs b/Tools/msi/launcher/launcher_files.wxs
index 9606dc6..589dee5 100644
--- a/Tools/msi/launcher/launcher_files.wxs
+++ b/Tools/msi/launcher/launcher_files.wxs
@@ -4,6 +4,7 @@
         <ComponentGroup Id="launcher_exe">
             <Component Id="py.exe" Directory="LauncherInstallDirectory" Guid="{B5107402-6958-461B-8B0A-4037D3327160}">
                 <File Id="py.exe" Name="py.exe" Source="py.exe" KeyPath="yes" />
+                <RegistryValue Root="HKMU" Key="Software\Python\PyLauncher" Value="[#py.exe]" Type="string" />
             </Component>
             <Component Id="pyw.exe" Directory="LauncherInstallDirectory" Guid="{8E52B8CD-48BB-4D74-84CD-6238BCD11F20}">
                 <File Id="pyw.exe" Name="pyw.exe" Source="pyw.exe" KeyPath="yes" />
@@ -12,12 +13,12 @@
             <Component Id="launcher_path_cu" Directory="LauncherInstallDirectory" Guid="{95AEB930-367C-475C-A17E-A89BFCD4C670}">
                 <Condition>NOT ALLUSERS=1</Condition>
                 
-                <RegistryValue KeyPath="yes" Root="HKMU" Key="Software\Python\PyLauncher\InstallDir" Value="[LauncherInstallDirectory]" Type="string" />
+                <RegistryValue KeyPath="yes" Root="HKMU" Key="Software\Python\PyLauncher" Name="InstallDir" Value="[LauncherInstallDirectory]" Type="string" />
                 <Environment Id="PATH_CU" Action="set" Name="PATH" Part="first" Value="[LauncherInstallDirectory]" />
             </Component>
             <Component Id="launcher_path_lm" Directory="LauncherInstallDirectory" Guid="{4A41C365-4E27-4D38-A6D1-4A01B4A6500C}">
                 <Condition>ALLUSERS=1</Condition>
-                <RegistryValue KeyPath="yes" Root="HKMU" Key="Software\Python\PyLauncher\InstallDir" Value="[LauncherInstallDirectory]" Type="string" />
+                <RegistryValue KeyPath="yes" Root="HKMU" Key="Software\Python\PyLauncher" Name="InstallDir" Value="[LauncherInstallDirectory]" Type="string" />
             </Component>
         </ComponentGroup>
     </Fragment>
diff --git a/Tools/msi/launcher/launcher_reg.wxs b/Tools/msi/launcher/launcher_reg.wxs
index 204b4ed..eef71c8 100644
--- a/Tools/msi/launcher/launcher_reg.wxs
+++ b/Tools/msi/launcher/launcher_reg.wxs
@@ -3,7 +3,7 @@
     <Fragment>
         <ComponentGroup Id="launcher_reg">
             <Component Id="file_association" Directory="LauncherInstallDirectory" Guid="{5AF84D9A-D820-456B-B230-6E0105A50276}">
-                <RegistryValue KeyPath="yes" Root="HKMU" Key="Software\Python\PyLauncher\AssociateFiles" Value="1" Type="integer" />
+                <RegistryValue KeyPath="yes" Root="HKMU" Key="Software\Python\PyLauncher" Name="AssociateFiles" Value="1" Type="integer" />
                 
                 <ProgId Id="$(var.TestPrefix)Python.File" Description="!(loc.PythonFileDescription)" Advertise="no" Icon="py.exe" IconIndex="1">
                     <Extension Id="$(var.FileExtension)" ContentType="text/plain">
diff --git a/Tools/msi/lib/lib.wxs b/Tools/msi/lib/lib.wxs
index b1aec75..2b04bcb 100644
--- a/Tools/msi/lib/lib.wxs
+++ b/Tools/msi/lib/lib.wxs
@@ -11,6 +11,7 @@
             <ComponentGroupRef Id="lib_py" />
             <ComponentGroupRef Id="lib_files" />
             <ComponentGroupRef Id="lib_extensions" />
+            <ComponentRef Id="OptionalFeature" />
         </Feature>
     </Product>
 </Wix>
diff --git a/Tools/msi/msi.props b/Tools/msi/msi.props
index bd22345..1d9f0f0 100644
--- a/Tools/msi/msi.props
+++ b/Tools/msi/msi.props
@@ -43,7 +43,7 @@
     </ItemGroup>
 
     <PropertyGroup>
-        <IntermediateOutputPath>$(MSBuildThisFileDirectory)\obj\$(Configuration)_$(Platform)\$(OutputName)</IntermediateOutputPath>
+        <IntermediateOutputPath>$(PySourcePath)PCBuild\obj\$(Configuration)_$(Platform)_Setup\$(OutputName)</IntermediateOutputPath>
         <IntermediateOutputPath Condition="'$(OutputSuffix)' != ''">$(IntermediateOutputPath)_$(OutputSuffix)</IntermediateOutputPath>
         <OutputPath Condition="'$(OutputPath)' == ''">$(BuildPath)</OutputPath>
         <OutputPath Condition="!HasTrailingSlash($(OutputPath))">$(OutputPath)\</OutputPath>
@@ -71,6 +71,7 @@
             NextMajorVersionNumber=$(MajorVersionNumber).$([msbuild]::Add($(MinorVersionNumber), 1)).0.0;
             Bitness=$(Bitness);
             PyDebugExt=$(PyDebugExt);
+            OptionalFeatureName=$(OutputName);
         </DefineConstants>
         <DefineConstants Condition="'$(CRTRedist)' != ''">
             $(DefineConstants);CRTRedist=$(CRTRedist);
@@ -112,9 +113,6 @@
         <LinkerBindInputPaths Include="$(CRTRedist)" Condition="'$(CRTRedist)' != ''">
             <BindName>redist</BindName>
         </LinkerBindInputPaths>
-        <LinkerBindInputPaths Include="$(CRTRedist)\$(Platform)" Condition="'$(CRTRedist)' != ''">
-            <BindName>crt</BindName>
-        </LinkerBindInputPaths>
     </ItemGroup>
 
     <Target Name="_ValidateMsiProps" BeforeTargets="PrepareForBuild">
diff --git a/Tools/msi/path/path.wxs b/Tools/msi/path/path.wxs
index 7e462e2..8b37936 100644
--- a/Tools/msi/path/path.wxs
+++ b/Tools/msi/path/path.wxs
@@ -9,7 +9,9 @@
         <Feature Id="DefaultFeature" AllowAdvertise="no" Title="!(loc.Title)" Description="!(loc.Description)">
             <Component Id="PrependPath_CU" Directory="InstallDirectory" Guid="*">
                 <Condition>NOT ALLUSERS=1</Condition>
-                <RegistryValue KeyPath="yes" Root="HKCU" Key="[REGISTRYKEY]\PrependPath" Value="1" Type="integer" />
+                <RegistryKey Root="HKCU" Key="[REGISTRYKEY]">
+                    <RegistryValue KeyPath="yes" Key="InstalledFeatures" Name="$(var.OptionalFeatureName)" Value="$(var.Version)" Type="string" />
+                </RegistryKey>
                 
                 <CreateFolder Directory="Scripts" />
                 <RemoveFolder Id="Remove_Scripts_CU" Directory="Scripts" On="uninstall" />
@@ -19,7 +21,9 @@
             </Component>
             <Component Id="PrependPath_LM" Directory="InstallDirectory" Guid="*">
                 <Condition>ALLUSERS=1</Condition>
-                <RegistryValue KeyPath="yes" Root="HKLM" Key="[REGISTRYKEY]\PrependPath" Value="1" Type="integer" />
+                <RegistryKey Root="HKLM" Key="[REGISTRYKEY]">
+                    <RegistryValue KeyPath="yes" Key="InstalledFeatures" Name="$(var.OptionalFeatureName)" Value="$(var.Version)" Type="string" />
+                </RegistryKey>
                 
                 <CreateFolder Directory="Scripts" />
                 <RemoveFolder Id="Remove_Scripts_LM" Directory="Scripts" On="uninstall" />
diff --git a/Tools/msi/pip/pip.wxs b/Tools/msi/pip/pip.wxs
index c46a868..19e9f5f 100644
--- a/Tools/msi/pip/pip.wxs
+++ b/Tools/msi/pip/pip.wxs
@@ -15,9 +15,7 @@
         <Condition Message="!(loc.NoPython)">PYTHON_EXE</Condition>
         
         <Feature Id="DefaultFeature" AllowAdvertise="no" Title="!(loc.Title)" Description="!(loc.Description)">
-            <Component Id="pip" Guid="*" Directory="InstallDirectory">
-                <RegistryValue KeyPath="yes" Root="HKMU" Key="[REGISTRYKEY]\EnsurePipRun" Value="1" Type="integer" />
-            </Component>
+            <ComponentRef Id="OptionalFeature" />
         </Feature>
         
         <?if $(var.Platform)~="x64" ?>
diff --git a/Tools/msi/tcltk/tcltk.wxs b/Tools/msi/tcltk/tcltk.wxs
index 5def5ed..0b83c5c 100644
--- a/Tools/msi/tcltk/tcltk.wxs
+++ b/Tools/msi/tcltk/tcltk.wxs
@@ -30,6 +30,7 @@
             <Component Id="idle_reg" Directory="InstallDirectory">
                 <RegistryValue KeyPath="yes" Root="HKMU" Key="[REGISTRYKEY]\Idle" Type="string" Value="[#Lib_idlelib_idle.pyw]" />
             </Component>
+            <ComponentRef Id="OptionalFeature" />
         </Feature>
         <Feature Id="AssociateFiles" AllowAdvertise="no" Title="!(loc.Title)" Description="!(loc.Description)">
             <ComponentGroupRef Id="tkinter_lib" />
diff --git a/Tools/msi/test/test.wxs b/Tools/msi/test/test.wxs
index de47785..f2ed64f 100644
--- a/Tools/msi/test/test.wxs
+++ b/Tools/msi/test/test.wxs
@@ -10,6 +10,7 @@
         <Feature Id="DefaultFeature" AllowAdvertise="no" Title="!(loc.Title)" Description="!(loc.Description)">
             <ComponentGroupRef Id="test_py" />
             <ComponentGroupRef Id="test_extensions" />
+            <ComponentRef Id="OptionalFeature" />
         </Feature>
     </Product>
 </Wix>
diff --git a/Tools/msi/tools/tools.wxs b/Tools/msi/tools/tools.wxs
index 366d4c6..8f8418a 100644
--- a/Tools/msi/tools/tools.wxs
+++ b/Tools/msi/tools/tools.wxs
@@ -9,6 +9,7 @@
         <Feature Id="DefaultFeature" AllowAdvertise="no" Title="!(loc.Title)" Description="!(loc.Description)">
             <ComponentGroupRef Id="tools_py" />
             <ComponentGroupRef Id="tools_scripts" />
+            <ComponentRef Id="OptionalFeature" />
         </Feature>
     </Product>
 </Wix>