Bukkit

What is the enhancement in mind? How should it look and feel?

Allow channel messages (such as joining and leaving a channel) to be hidden.

Please provide any additional information below.

The server could set a default channel message visibility status that a channel would override (it defaults to the server wide setting in case a channel does not contain this visibility option). Each player can decide to override the channel setting to a certain degree.

The player should be able to hide channel event messages if the channel's visibility status is set to display join/leave messages.

The player should not be able to show channel even messages if the channel's visibility status is set to hide join/leave messages.