Fix for #6377 - Prevent 3mf files from overwriting filament/printer settings

+ Ask about action on load of project even if print bed isn't empty

src/slic3r/GUI/GUI_App.cpp

@@ -772,8 +772,15 @@ void GUI_App::post_init()
             this->mainframe->load_config_file(this->init_params->load_configs.back());
         // If loading a 3MF file, the config is loaded from the last one.
         if (!this->init_params->input_files.empty()) {
+#if 1 // #ysFIXME_delete_after_test_of
+            wxArrayString fns;
+            for (const std::string& name : this->init_params->input_files)
+                fns.Add(from_u8(name));
+            if (plater()->load_files(fns) && this->init_params->input_files.size() == 1) {
+#else
             const std::vector<size_t> res = this->plater()->load_files(this->init_params->input_files, true, true);
             if (!res.empty() && this->init_params->input_files.size() == 1) {
+#endif
                 // Update application titlebar when opening a project file
                 const std::string& filename = this->init_params->input_files.front();
                 if (boost::algorithm::iends_with(filename, ".amf") ||