The clamshell mode-related functionality that allows an external display to be used as the main display for a MacBook Pro whilst allowing the MBP's lid to remain open and its own display turned off seems to be broken under Lion.
A lot of people want this functionality back - not just for better wifi reception, but also because having the lid open enables the MBP to remain VERY MUCH cooler in operation than it would with the lid closed.
This functionality needs to be restored to Lion urgently. I regard its omission as a bug, not least because Apple's online instructions for how clamshell mode should work remain unchanged. I would encourage you to submit your own direct request / bug report for this issue via the feedback form here:
Support today quoted Apple's engineers as saying it is "expected behaviour" under Lion for the MBP's internal display to reactivate upon opening the lid, even if you want to use only your external display. A new version of the clamshell mode-related knowledgebase article (replacing HT3131) is due shortly confirming this.
This is despite:
- the obvious temperature-related benefits that were achievable (under Snow Leopard) by opening your MBP lid whilst continuing to output solely to, say, a 27" cinema display
- potential wifi connectivity benefits of having the lid open
- the waste of energy and inefficient use of graphics processing power in needlessly running two active screens (ie if running your MBP in clamshell mode would otherwise make it too hot and/or noisy or you need it open for wifi)
- the negative longer-term impact on the battery and other components from running the MBP any hotter than it needs to be.
To have any hope of getting the previous behaviour back, we need to lobby Apple to change how Lion handles clamshell mode. Options available to them include changing Lion's expected behaviour or adding a user-selectable option within System Preferences.
I know you've already submitted your own feedback, Ovate, but others can still do so (please) below. Now that this situation is clarified as intentional, user feedback has become all the more important.
Potential solution: Apple wants your forum feedback
Please see a post in the following thread and reply to it as you wish. Apple has reportedly requested us to provide evidence within the forum thread in support of our desire to have the "open lid with screen off" option reinstated (eg the significance of operating temperature differences, levels of reduction in wifi reception, etc). They may then address our concerns with a Lion update.
Why oh why did Apple come up with the clamshell thing? I don't know about the pre-unibody MBPs but unibody MBPs fan pushes the warm air upwards from the bottom of the screen. When the screen is down and MBP is working hard, that hot hair hits the screen hard and I suspect it could deform the glass or so some kind of damage to the screen in it goes on long enough. Right?
I'm getting more and more disappointed with MBP design and these moronic limitations.
SOLUTION / FIX
Open System Preferences, Display, Arrangement - then:
Move the WHITE "APP LAUNCH BAR" to the monitor you want as the primary.
For a picture of this - click LINK here.
I literally took my external monitor to the Apple Genius Bar with my 1999 MBP & New 2012 MBP in hand. The tech was stumped..... Thank goodness that the manager knew this trick.
1 - Why can't you write the words "APP LAUNCH BAR" inside the white box? This was not obvious at all !!
2 - Why can't you make it default to keep the "APP LAUNCH BAR" on 'starting' same monitor.
-- Snow Leopard does not move the launch bar to the external monitor when you plug it in !
I just could not accept that my brand new FEB2012 MacBookPro 17 could no longer use an external monitor. Well it can. But 'we' users have to manually make this change EACH TIME we plug into the external monitor.
Apple - at least it works - even if it is ugly. Cost me a lot of TIME to figure this out.
I hope this helps others in the same boat.
Yes I think most people know about moving the Menu Bar to the other monitor. But it still leaves the MBP monitor active but useless during a video on external display. Clamshell mode is particularly a bad idea during video play.
So this is still a big problem. Finally I started using a magnet to fool MBP into entering clamshell mode. which is a shameful way to use such an expensive well made machine. Sigh!