Why does the lock interface of SMS application change color?

The discoloration of the locking interface of SMS application is probably the problem of the display screen.

Application lock is to encrypt the applications you want to protect, and anyone who wants to access these applications needs to enter a password. Maybe everyone will say that there are too many such applications, but none of them can protect them well. Some will be invalid after pressing the home button, and some can enter the protected application at will by entering the password once. Therefore, you can lock and unlock an application by clicking it in the application list.