I am writing to suggest some new features that I believe would be very useful for your users.

Description:

• Pin message: Allow users to pin important messages to the top of their chats, so that they can easily find them later. This would be especially useful for group chats, where it can be difficult to keep track of all the messages.
• Important message: Add an option to send an important message that triggers a reminder every 2 minutes on the screen when the phone is locked. This would be very useful for ensuring that important messages are not missed.
• Notification color: Allow users to change the notification color that shows on the lock screen to red, blue, or green. This would make it easier for users to identify important messages at a glance.

Rationale:

These features would make WhatsApp even more useful and convenient for its users. The pin message feature would help users to keep track of important messages, the important message feature would help to ensure that important messages are not missed, and the notification color feature would make it easier for users to identify important messages at a glance.

Implementation:

The pin message feature could be implemented by adding a new button to the chat screen that allows users to pin a message. The pinned message would then appear at the top of the chat screen.

The important message feature could be implemented by adding a new option to the message sending menu that allows users to send an important message. When an important message is sent, a notification would appear on the recipient's screen every 2 minutes until they have acknowledged the message.

The notification color feature could be implemented by adding a new setting to the WhatsApp app that allows users to change the notification color.