新的布局语法，修复部分编译警告

example/src/main.cpp

@@ -75,9 +75,7 @@ int main(int argc, char* argv[]) {
 		mslot(mbutton)
 		.margin({10})
 		.visibility(visibility_t::visible)
-		[
-			text_block
-		]
+		(text_block)
 	);
 
 	// const auto button2 = mnew(mbutton)
@@ -89,14 +87,12 @@ int main(int argc, char* argv[]) {
 
 	const auto& window = mwindow::create({ 800, 600 }, L"Hello, World!");
 	window->set_content(
-		mborder()
+		mnew(mborder)
 		[
 			mslot(mborder)
 			.h_alignment(horizontal_alignment_t::center)
 			.v_alignment(vertical_alignment_t::center)
-			[
-				button
-			]
+			(button)
 		]
 	);