diff --git a/cmake/backend/emscripten.cmake b/cmake/backend/emscripten.cmake
index 7f93cb3..8057ab8 100644
--- a/cmake/backend/emscripten.cmake
+++ b/cmake/backend/emscripten.cmake
@@ -134,6 +134,7 @@ function(nui_add_emscripten_target)
                 ${NUI_ADD_EMSCRIPTEN_TARGET_ARGS_CMAKE_OPTIONS}
                 "-DNUI_NPM=${NUI_NPM}"
                 "-DNUI_NODE=${NUI_NODE}"
+                "-DCMAKE_EXPORT_COMPILE_COMMANDS=ON"
                 -DNUI_INLINE_EXTRACTOR_TARGET_FILE=$<TARGET_FILE:inline-parser>
                 -DNUI_INLINE_INJECTOR_TARGET_FILE=$<TARGET_FILE:inline-injector>
                 -DNUI_MODULE_BUILD_DIR=${CMAKE_BINARY_DIR}/module_${NUI_ADD_EMSCRIPTEN_TARGET_ARGS_TARGET}
diff --git a/cmake/frontend/emscripten.cmake b/cmake/frontend/emscripten.cmake
index 7b08234..219eb9f 100644
--- a/cmake/frontend/emscripten.cmake
+++ b/cmake/frontend/emscripten.cmake
@@ -1,7 +1,7 @@
 function(nui_prepare_emscripten_target)
     cmake_parse_arguments(
         NUI_PREPARE_EMSCRIPTEN_TARGET_ARGS
-        "NO_INLINE;NO_INLINE_INJECT"
+        "NO_INLINE;NO_INLINE_INJECT;LEAN_INDEX_HTML"
         "TARGET;PREJS;STATIC;UNPACKED_MODE"
         "EMSCRIPTEN_LINK_OPTIONS;EMSCRIPTEN_COMPILE_OPTIONS;PARCEL_ARGS;NPM_INSTALL_ARGS"
         ${ARGN}
@@ -23,11 +23,16 @@ function(nui_prepare_emscripten_target)
         set(NUI_DEFER_INLINE_SCRIPTS_TAG "defer")
     endif()
 
+    set(NUI_LEAN_HTML "nolean")
+    if (NUI_PREPARE_EMSCRIPTEN_TARGET_ARGS_LEAN_INDEX_HTML)
+        set(NUI_LEAN_HTML "lean")
+    endif()
+
     set(INLINER_COMMAND "")
-    if (NOT NO_INLINE)
+    if (NOT NUI_PREPARE_EMSCRIPTEN_TARGET_ARGS_NO_INLINE)
         nui_enable_inline(TARGET ${NUI_PREPARE_EMSCRIPTEN_TARGET_ARGS_TARGET} RELATIVE_TO ${CMAKE_CURRENT_SOURCE_DIR})
-        if (NOT NO_INLINE_INJECT)
-            set(INLINER_COMMAND COMMAND ${NUI_INLINE_INJECTOR_TARGET_FILE} "${CMAKE_BINARY_DIR}/static/index.html" "${CMAKE_BINARY_DIR}/nui-inline/inline_imports.js" "${CMAKE_BINARY_DIR}/nui-inline/inline_imports.css" ${NUI_DEFER_INLINE_SCRIPTS_TAG})
+        if (NOT NUI_PREPARE_EMSCRIPTEN_TARGET_ARGS_NO_INLINE_INJECT)
+            set(INLINER_COMMAND COMMAND ${NUI_INLINE_INJECTOR_TARGET_FILE} "${CMAKE_BINARY_DIR}/static/index.html" "${CMAKE_BINARY_DIR}/nui-inline/inline_imports.js" "${CMAKE_BINARY_DIR}/nui-inline/inline_imports.css" ${NUI_DEFER_INLINE_SCRIPTS_TAG} ${NUI_LEAN_HTML})
         endif()
     endif()
 
diff --git a/nui/include/nui/event_system/listen.hpp b/nui/include/nui/event_system/listen.hpp
index c2f5e82..c87c281 100644
--- a/nui/include/nui/event_system/listen.hpp
+++ b/nui/include/nui/event_system/listen.hpp
@@ -72,4 +72,16 @@ namespace Nui
     {
         return listen(eventContext, obs, std::function(std::move(onEvent)));
     }
+
+    template <typename ValueT, typename FunctionT>
+    void listen(std::shared_ptr<Observed<ValueT>> const& obs, FunctionT onEvent)
+    {
+        return listen(globalEventContext, obs, std::function(std::move(onEvent)));
+    }
+
+    template <typename ValueT, typename FunctionT>
+    void listen(Observed<ValueT> const& obs, FunctionT onEvent)
+    {
+        return listen(globalEventContext, obs, std::function(std::move(onEvent)));
+    }
 }
\ No newline at end of file
diff --git a/nui/include/nui/event_system/observed_value.hpp b/nui/include/nui/event_system/observed_value.hpp
index c9cae00..4291ef3 100644
--- a/nui/include/nui/event_system/observed_value.hpp
+++ b/nui/include/nui/event_system/observed_value.hpp
@@ -15,6 +15,7 @@
 #include <deque>
 #include <string>
 #include <cassert>
+#include <set>
 
 namespace Nui
 {
@@ -1286,7 +1287,7 @@ namespace Nui
                 : observed_{&observed}
             {}
 
-            inline T value() const
+            inline T const& value() const
             {
                 return observed_->value();
             }
diff --git a/nui/test/nui/CMakeLists.txt b/nui/test/nui/CMakeLists.txt
index 1aad13a..4e10955 100644
--- a/nui/test/nui/CMakeLists.txt
+++ b/nui/test/nui/CMakeLists.txt
@@ -5,7 +5,7 @@ add_library(nui-frontend-mocked STATIC ${NUI_FRONTEND_SOURCES})
 
 target_include_directories(nui-frontend-mocked PUBLIC emscripten_mock ${CMAKE_CURRENT_LIST_DIR}/../../include)
 
-find_package(Boost REQUIRED)
+find_package(Boost CONFIG REQUIRED)
 
 target_link_libraries(nui-frontend-mocked PUBLIC
     libcpppre
diff --git a/tools/inline_injector/main.cpp b/tools/inline_injector/main.cpp
index 12e346e..7089d28 100644
--- a/tools/inline_injector/main.cpp
+++ b/tools/inline_injector/main.cpp
@@ -21,11 +21,11 @@ std::string readFile(const std::filesystem::path& path)
 
 int main(int argc, char** argv)
 {
-    if (argc != 5)
+    if (argc != 6)
     {
-        std::cout
-            << "Expected 4 argument: <index.html> <import_scripts> <import_styles> <import_scripts_defer>, but got "
-            << argc - 1 << "\n";
+        std::cout << "Expected 4 argument: <index.html> <import_scripts> <import_styles> <import_scripts_defer> "
+                     "<lean_html>, but got "
+                  << argc - 1 << "\n";
         return 1;
     }
 
@@ -33,6 +33,7 @@ int main(int argc, char** argv)
     const auto importScripts = std::filesystem::path{argv[2]};
     const auto importStyles = std::filesystem::path{argv[3]};
     const auto importScriptsDefer = std::string{argv[4]} == "defer" ? true : false;
+    const auto leanHtml = std::string{argv[5]} == "lean" ? true : false;
 
     std::string indexHtml;
     try
@@ -57,8 +58,17 @@ int main(int argc, char** argv)
         relativeImportScriptsFile.generic_string() + "\";\n\t</script>\n";
     const std::string importStylesHtml =
         "\t<style>\n\t\t@import \"" + relativeImportStylesFile.generic_string() + "\";\n\t</style>\n";
-    const std::string importBinIndexHtml =
-        "\t<script type=\"module\" defer>\n\t\timport \"" + binIndex.generic_string() + "\";\n\t</script>\n";
+
+    std::string importBinIndexHtml;
+    if (!leanHtml)
+    {
+        importBinIndexHtml =
+            "\t<script type=\"module\" defer>\n\t\timport \"" + binIndex.generic_string() + "\";\n\t</script>\n";
+    }
+    else
+    {
+        importBinIndexHtml = "\t<script type=\"module\" defer src=\"" + binIndex.generic_string() + "\"></script>\n";
+    }
 
     // find end of header </head> from behind in indexHtml:
     auto headEnd = indexHtml.rfind("</head>");