Would a necro warning system be feasable ?

Every now and then someone will necro a thread seemingly by accident. Would it be possible to mod the board so that if a thread hasn't been posted in for a specific time interval then one of these will happen to it:

- Automatic thread lock.

- If someone goes to post in the thread an "Are you sure" message will come up saying exactly how long the thread has been dead for and warning them that they are about to necro.

Both methods should stop accidental necros, choosing between them should be decided by the policies on what we should do if we actually have something significant to add to a dead thread.

Bilateralrope, while the first suggestion is not an option (we do tell people to use search especially in Sardelac) I'm not sure if there's a vb hack out there with that feature. I'll look though as I do think that would be a great suggestion.