while searching Mellies room you will find a paper on the desk behind the bed, on the paper there is an handwritten series of numbers: "10966 / 2".
If you calculate it you get 5483, and that was the code that should be used to open the safe. Today any four digit code will work...

I tried a code that made sense, and it worked. It's only in now reading later comments in the thread that I see the code was turned off and any code would work.

That being said, if there really is a paper in the room with the code on it, then the hunt for items should be changed. Already I had a bit of a problem with that puzzle (I didn't actually have problems finding the right answer, but I had some issue with game play on the wrong answers). With the images small, and I think my display often shows images darker than others (making a hunt for a hidden item game very difficult), I generally couldn't tell what I was clicking on. All I knew was that the cursor changed. Sometimes clicking would zoom in the display, and sometimes I'd get a, "sorry, wasted try."

The way I would suggest the hunt should work... all the clickable areas remain as they are, but when the player clicks on a "guess" rather than a change viewpoint, a question is presented to the player. Your choice whether you show a blow-up of the item in question and/or name the item (i.e. You've found a banana. Would you like to guess this?). Either way, the player should know they are about to make a guess, and know what item they are guessing.

This changes the nature of the game. Currently people can be penalized for trying to explore and look at the room. It is negative feedback that makes players shy away from exploring. If you give players the option to "cancel" any guess, then they feel they are rewarded by searching because they get to find more objects, rather than "losing" because they clicked in the wrong place.