Check if someone else replied to the thread before posting
 

There's a mod for vB 3.7.0 called Check Post (https://vborg.vbsupport.ru/showthread.php?t=171227), which warns you if someone else replied to the thread while you were sending the message instead than posting it, after clicking "send message".

Clicking a second time would just post the message.

Well, it used to work on vB 4.0 too, until.. a few versions ago, where it started to give problems (like errors on top of the page), so I had to disable it.

Now, can anyone tell me if there's another mod like that which does the same, for vB 4.0.6?