With lightuserdata, you give the pointer to it: `void
lua_pushlightuserdata (lua_State *L, void *p);` In this use case, that's
important, because you need to find the C object (Window handle) inside of
Lua. You can't do that with userdata, unless you want to manually do that
using some other kind of uuid magic.
Not the C object (Window handle), but instead the *pointer*, because the
handle that you receive from Windows can be pushed on the stack, like so:
```
lua_rawgetp(L, LUA_REGISTRYINDEX, (void *) ptr_my_whandle);
* ud_myobj =(window_obj *) lua_touserdata(L, -1);
luaL_checkudata( L, -1, MY_LIB_NAME);
```
Hopefully that's somewhat clearer
