Add VS2026 multi-config section and fix VS2022 statement in BUILDING.md

BUILDING.md

@@ -413,7 +413,7 @@ are defined within the "cacheVariables" section. Modify/Add your own as required
 to indicate to VS 2022 where to find some libraries (.lib) or include files (.hpp), those are specific to this
 example and may not apply to your setup.
 
-<CMakePreset.json file example>
+<CMakePresets.json file example>
 
 {
   "version": 3,
@@ -430,9 +430,9 @@ example and may not apply to your setup.
       "binaryDir": "${sourceDir}/build",
       "cacheVariables": {
         "CMAKE_CONFIGURATION_TYPES": "Debug;Release;RelWithDebInfo",
-	      "CMAKE_BUILD_TYPE": "Debug",
-	      "CMAKE_SUPPRESS_DEVELOPER_WARNINGS": "1",
-	      "CMAKE_PREFIX_PATH": "C:/Qt/6.7.3/msvc2022_64;C:/Dev/Libs/exiv2-0.28.7/lib/cmake/exiv2",
+	    "CMAKE_BUILD_TYPE": "Debug",
+	    "CMAKE_SUPPRESS_DEVELOPER_WARNINGS": "1",
+	    "CMAKE_PREFIX_PATH": "C:/Qt/6.7.3/msvc2022_64;C:/Dev/Libs/exiv2-0.28.7/lib/cmake/exiv2",
         "QT_QMAKE_EXECUTABLE": "C:/Qt/6.7.3/msvc2022_64/bin/qmake.exe",
         "ENABLE_SCRIPTING": "ON",
         "ENABLE_GPS": "ON",
@@ -473,7 +473,7 @@ example and may not apply to your setup.
 on your main system drive. Add the path to your user/system environment variables PATH to allow Stellarium to 
 discover them during runtime.
 
-Open Visual Studio 2022 (run as admin). Continue wihtout code.
+Open Visual Studio 2022. Continue without code.
 
 If you want to use a specific cmake.exe go to Tools -> Options, navigate to Cmake -> General and fill the appropriate
 checkbox and path. Otherwise VS 2022 will use it own cmake.exe tool. The path of an external cmake should be included
@@ -499,26 +499,112 @@ Then build by typing this command in the Developer Command Prompt:
 
 cmake --build --preset Release
 
-Redo the same process for the last build, ie. RelWithDebInfo.
+Redo the same process for the last build, i.e. RelWithDebInfo.
 
 cmake --build --preset RelWithDebInfo
 
-**Note** : Once all three builds are completed, YOU MUST REMAIN in the Folder View of VS 2022 for all subsequent actions. 
-Do not open any of the Stellarium.sln files generated by VS 2022. This may disrupt the multi-config links between Visual 
-Studio and Qt.
-
-At this point you can run any executables (Start Debugging F5 or Start without Debugging Ctrl-F5). Just ensure you specify 
-which executable by setting it as 'Set as Startup Item' prior 
-
 To run test suites (if ENABLE_TESTING = ON), use again the Developer Command Prompt. Navigate to <stel_dir>+"\build. 
 Then type one of these three commands:
 
 ctest -C Debug
 ctest -C Release
 ctest -C RelWithDebInfo
 
-If you edit the code of your source files, select from the Configuration dropdown list the configuration you want to rebuilt 
-and use again the Developer Command Prompt with the appropriate command : cmake --build --preset <build-type> 
+Once all three builds are completed and unit testing is verified you can close the folder view and open the Stellarium Solution
+which is located here : stellarium/build/Stellarium.sln 
+
+File --> Close Folder
+File --> Open --> Project/Solution...
+
+Visual Studio 2022 should open Stellarium in Debug/x64 configuration. The Solution Explorer should display all the Stellarium projects. 
+Right click on the stellarium project to 'Set as Startup Project'. At this stage you are ready to further modify/rebuild the code, test and 
+run Stellarium, or any of the test cases projects listed in the Solution Explorer view, after selecting them as start-up project.
+
+Note: To work on the Release or RelWithDebInfo configuration first select it from the dropdown top menu of Visual Studio 2022.
+
+#### For Visual Studio 2026 (multi-configuration):
+
+You can also used this newly released version of Visual Studio (November 2025) to build and develop Stellarium. This release fixes the bug 
+of VS 2022 for the building steps and in a sense simplify the building process of Stellarium. Here are the changes to the process described
+above for Visual Studio 2022 (multi-configuration)
+
+Use a slightly different CMakePresets.json file, and adapt it to your development environment.
+
+<CMakePresets.json file example for VS 2026>
+{
+  "version": 3,
+  "cmakeMinimumRequired": { "major": 3, "minor": 21, "patch": 0 },
+  "configurePresets": [
+    {
+      "name": "vs2026-multi-config",
+      "displayName": "Stellarium (VS2026 Multi-Config)",
+      "description": "Unified build tree for Debug, Release, and RelWithDebInfo using Visual Studio 2026",
+      "generator": "Visual Studio 18 2026",
+      "architecture": {
+        "value": "x64"
+      },
+      "binaryDir": "${sourceDir}/build",
+      "cacheVariables": {
+        "CMAKE_CONFIGURATION_TYPES": "Debug;Release;RelWithDebInfo",
+	    "CMAKE_BUILD_TYPE": "Debug",
+	    "CMAKE_SUPPRESS_DEVELOPER_WARNINGS": "1",
+	    "CMAKE_PREFIX_PATH": "C:/Qt/6.7.3/msvc2022_64;C:/Dev/Libs/exiv2-0.28.7/lib/cmake/exiv2",
+        "QT_QMAKE_EXECUTABLE": "C:/Qt/6.7.3/msvc2022_64/bin/qmake.exe",
+        "ENABLE_SCRIPTING": "ON",
+        "ENABLE_GPS": "ON",
+        "ENABLE_TESTING": "ON",
+        "ENABLE_NLS": "ON",
+        "SCM_SHOULD_ENABLE_CONVERTER": "TRUE",
+        "GETTEXTPO_LIBRARY": "C:/Dev/Libs/gettextpo/lib/libgettextpo.lib",
+        "GETTEXTPO_INCLUDE_DIR": "C:/Dev/Libs/gettextpo/include",
+        "LIBTIDY_LIBRARY": "C:/Dev/Libs/libtidy/lib/libtidy.lib",
+        "LIBTIDY_INCLUDE_DIR": "C:/Dev/Libs/libtidy/include",
+        "EXIV2_LIBRARY": "C:/Dev/Libs/exiv2-0.28.7/lib/exiv2.lib",
+        "EXIV2_INCLUDE_DIR": "C:/Dev/Libs/exiv2-0.28.7/include",
+        "exiv2_DIR": "C:/Dev/Libs/exiv2-0.28.7/lib/cmake/exiv2",
+        "Qt6LinguistTools_DIR": "C:/Qt/6.7.3/msvc2022_64/lib/cmake/Qt6LinguistTools"
+      }
+    }
+  ],
+  "buildPresets": [
+  {
+    "name": "Debug",
+    "configurePreset": "vs2026-multi-config",
+    "configuration": "Debug"
+  },
+  {
+    "name": "Release",
+    "configurePreset": "vs2026-multi-config",
+    "configuration": "Release"
+  },
+  {
+    "name": "RelWithDebInfo",
+    "configurePreset": "vs2026-multi-config",
+    "configuration": "RelWithDebInfo"
+  }
+  ]
+}
+
+Note: To use 'Visual Studio 18 2026' generator, you need the latest version of CMake, version 4.2.0
+
+Open Visual Studio 2026. Open the Stellarium folder.
+
+File -> Open -> Folder... and select <stel_dir>
+
+VS 2026 will automatically detect the CMakePresets.json file and start to configure the first Preset Configuration which
+is 'Debug'. To build the Debug configuration, select Build --> Build All from the top menu of VS 2026. Building information should be 
+displayed in the Build Output window. If the Debug build was successful you should see the executable stellarium.exe generated in the 
+sub-directory <stel_dir>\build\src\Debug.
+
+If the Debug build was successful, select from the Configuration dropdown menu of VS 2026, the next configuration specified in
+the CMakePresets.json file, i.e Release in this case.  VS 2026 will start cmake to configure the build. Upon completion, to build the 
+Release configuration select Build --> Build All from the top menu of VS 2026. If the Release build was successful you should see the
+executable stellarium.exe generated in the sub-directory <stel_dir>\build\src\Release. Repeat the same steps for the RelWithDebInfo 
+configuration. If the RelWithDebInfo build was successful you should see the executable stellarium.exe generated in the 
+sub-directory <stel_dir>\build\src\RelWithDebInfo.
+
+Upon completion of the build process for all three configurations, you can close the folder and open the Stellarium solution, 
+the same way as it is described for VS 2022 above.
 
 
 ### Supported CMake parameters