diff --git a/CMakeLists.txt b/CMakeLists.txt
index 036843c..0979898 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,22 +1,9 @@
 cmake_minimum_required(VERSION 3.30)
 project(LearnGtk4 LANGUAGES CXX)
 
-include(FetchContent)
 find_package(PkgConfig REQUIRED)
 pkg_check_modules(GTKMM4 REQUIRED IMPORTED_TARGET gtkmm-4.0)
 
-fetchcontent_declare(BillySheet
-        GIT_REPOSITORY https://gitea.pcornatcloud.fr/Pcornat/BillySheet.git
-        GIT_SUBMODULES_RECURSE ON
-        GIT_SHALLOW ON
-        DOWNLOAD_EXTRACT_TIMESTAMP OFF
-        OVERRIDE_FIND_PACKAGE
-)
-option(BILLY_ENABLE_TESTS "Enable Unit testing target" OFF)
-fetchcontent_makeavailable(BillySheet)
-
-find_package(BillySheet CONFIG REQUIRED)
-
 find_program(CCACHE_FOUND ccache)
 if (CCACHE_FOUND)
     message(STATUS "ccache found !")
@@ -99,4 +86,4 @@ target_compile_definitions(LearnGtk4 PUBLIC $<$<CONFIG:Debug>:_GLIBCXX_DEBUG>)
 target_compile_definitions(assimp PUBLIC $<$<CONFIG:Debug>:_GLIBCXX_DEBUG>)
 target_compile_options(LearnGtk4 PUBLIC ${COMPILE_FLAGS})
 target_link_options(LearnGtk4 PUBLIC ${LINKER_OPTIONS})
-target_link_libraries(LearnGtk4 PkgConfig::GTKMM4 assimp spdlog_header_only BillySheet)
+target_link_libraries(LearnGtk4 PkgConfig::GTKMM4 assimp spdlog_header_only)
diff --git a/app_win_2_back.cpp b/app_win_2_back.cpp
index aa743ed..ff5dac1 100644
--- a/app_win_2_back.cpp
+++ b/app_win_2_back.cpp
@@ -112,10 +112,8 @@ namespace gui_to_app {
     void AppWin2Back::on_quit() noexcept {
         auto windows = get_windows();
         for (auto *window: windows) {
-            if (window != nullptr) {
-                window->set_visible(false);
-                delete window;
-            }
+            window->set_visible(false);
+            delete window;
         }
         quit();
     }