Update examples for testing modules

examples/dom/vbox_hbox.cpp

@@ -2,12 +2,21 @@
 // Use of this source code is governed by the MIT license that can be found in
 // the LICENSE file.
 #include <stdio.h>                  // for getchar
+
+#ifndef FTXUI_BUILD_MODULES
 #include <ftxui/dom/elements.hpp>   // for filler, text, hbox, vbox
 #include <ftxui/screen/screen.hpp>  // for Full, Screen
+#endif 
+
 #include <memory>                   // for allocator
 
+#ifndef FTXUI_BUILD_MODULES
 #include "ftxui/dom/node.hpp"      // for Render
 #include "ftxui/screen/color.hpp"  // for ftxui
+#else
+import ftxui.dom;
+import ftxui.screen;
+#endif
 
 int main() {
   using namespace ftxui;