Change block structure to procedure for main

src/x11ex.nim

@@ -85,8 +85,10 @@ proc handle_event* (hello: var Hello) =
   else:
     discard
 
-block:
+proc main =
   var hello = createHello(800, 600, "Hello!")
   defer: hello.close()
   while hello.running:
     hello.handle_event()
+
+main()