Fix false foul

[Hyperseeker]

There's a rare error arising from the sequences of key presses that goes as follows:

1. Player presses the last correct key of the password
2. Immediately after, players presses an incorrect key
3. The password is successfully solved, new password is generated, but before it's rendered, the "foul" signal (currently a flash of red by the edges of the window) appears

While not critical, it may leave the player with unduly worry about losing progress in an intense game.

Solution pending.