Well, I believe correct me if i'm wrong you can do this. In the level editor put a interact area over the window and call it whatever you want. Now, i'm not currently home so I don't know for sure if the will work but I believe this is what you would have to do.
////////////////////////////
// Run when entering map
void OnStart()
{
SetEntityPlayerInteractCallback("area_name", "WindowDoor", true);
}
void WindowDoor(string &in asEntity)
{
ChangeMap(
MapName, StartPos, StartSound, EndSound);
}
That should work... you can just add whatever other effects you want to that too. But that should be all you need to do to make what you want work. Tell me how it works out too! And btw, I believe what you would put for the "StartPos" would be just blank if you haven't named the spawn area in the next level the window would be taking you too. But if not, just enter the name of the desired spawn area and everything should just be fine. Hope this helps!
Just saw the comment below lol. Think I read you post wrong.
Because with mine I think it would just teleport you into the next map with no loading screen.