Shoutbox

Create a quicktext.

Go to the quicktexts section of MP!L, 'Create a standalone message or message group'.
Then in the 'Fast send shortcut' section, enter /b (or whatever command you like).
In the Message(s) bit, enter:

code:

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/all brb
/brb

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Change the 'line breaks' radio button to the one that reads 'create multiple messages'

The result of all of this means that when you type /b in a conversation and press enter, 'brb' will be sent to all open conversations, and your status will automatically change to be right back.