First of all, do not use both Idle functions at the same time.
(You can use them at the same time, but be very aware of exactly what those functions do and how they work, otherwise you will only be confussed (as it shows now 
))
To let the Idle function of Plus! only react when your status is "Online" or "Idle", just as MSN Messenger, you need to set an advanced registry key named
AutoAwayAlways.
For more information on this see the
official help pages of Messenger Plus! and more specifically here:
http://www.msgplus.net/help_registry.php. Everything is explained on those pages. (including a link to a utility which can set those special registry settings for you, without the need of manually editing the registry)
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