When you are extended desktop mode, it is like the computer has added more destop (but without the menu bar). You can move your mouse there and can drag a program window there if you want. MS PowerPoint and Keynote will, in presenter mode, put the presenter panel on one screen and the full presentation on the other.
I believe you are correct in that you need to be hooked up to the projector to see the mirroring option. I am at my desktop currenlty so I can't make a definitive call. However, a little app from the app store called "Display Menu" puts all the important controls up in the menu bar like it was on past Mac OSes. I use it all the time. It has the ability to adjust resolution easily and turn on mirroring.
This is the same problem I have, and no solutions since posting last month. Brand-new MBP 13 Retina set to mirror the screen to the projector, and does that for every other program EXCEPT iPhoto, which is what I want to display. For iPhoto, projector displays only my "constellation" homescreen. I'm reduced to carrying around my heavy 7-year-old Dell Windows 7 laptop, which hooks up to the projector instantly.
Thanks for suggesting that adapter. I had my problems when using the Apple adapter. Since using the Cirago active adapter I've had no problems so far. The connect 'just works' without option key, plugging-in in order, etc.., and it has worked with two MacBooks. I have not explored the tech of the 'active' adapter but seems to allow components to recognize one and other...I wonder if problems started when Apple began using the same port for multiple protocols i.e. thunderbolt. This has apparently been a problem for many and Apple should make the fix or fixes known even if it requires hardware they don't make (though they should).
I thought I might just weigh in to this thread with some vaguely interesting info.
I just upgraded my old MBP (snow leopard) to the new MBP Retina (mountain lion). My old MBP worked perfect with my ACER data projector, first time every time.
Then yesterday I took the new MBP to a lecture and when I tried connecting the data projector to the MPB (via the old DVI miniport I'd been successfully using on the old MBP) all that projected onto the wall was the "solar system screensaver" image. I couldn't see what was on my MBP screen, which at the time was just the Finder screen. I tried looking at Google Chrome, iTunes and a powerpoint presentation (using Office For Mac) - nothing but the solar system. I assumed there was a problem with the new mountain lion software and after reading through many different threads have seen solutions regarding using a genuine Apple miniport (which I am already), or at least a "newer" one which may be more compatible with the thunderbolt connection, or downloading the Display Menu App, or going into System Preferences/Displays.
After much cursing Apple for making my life ****, I eventually stumbled upon the fact that the powerpoint presentation was working the whole time, but now (for some reason) it appears the presentation only displays via the data projector once I switch Powerpoint into "Slideshow" - then it displayed fine. I'm assuming it is some new way of allowing me to work on my computer without the audience seeing what I'm doing, and then I can turn on "slideshow" and then they can see the presentation. So it seems I don't have a problem after all.
Admittedly I haven't tried displaying the general screen (finder / internet etc) but I have now also downloaded the Display Menu App (free) and can see that this does solve my problem anyway, and can view anything via the data projector with this app working.
Hope this helps people.
I had the exaxt issue you described. Normally I use my MacBookAir for lectures at university using the lecture theater projector and had not any problems.
However, yesterday, I was working with an NPO and used their prohector and only the Mountain Lion "solar screen saver" wallpaper appeared. But, like you, when I actually started the PowerPoint Presentation slide show, it showed up on the proejctor.
Since I have to give a very important presentation and workshop on Sunday, I contacted Apple Care Support here in Japan to find out what the issue is. I was transferred to a top enginner who quickly knew how to troubleshoot. This solution does not requre getting new software or an official Apple VGA adapter.
Basically, Mountain Lion remembers the mirror setting for every different VGA projector you use. Most projectors have the same the settings, so normally there is no need to have Mountain Lion remember a setting on a different computer. However, depending on the projector, Mountain Lion sees the projector as a new projector. In this case, the mirroring default is no checked and only the solar screen saver appears. Fortunately, the troubleshooting in very simple.
Following these steps:
1. Connect the Mac and VGA adapter to the projector when the projector is on.
2. Go to System Preferences > Displays.
3. Since the computer is connected to the projector, an extra tab between "Display" and "Color" will appear. (Sorry I cannot remember the name of the middle tab as I don't have projector to connect to at the moment.) When the computer is not connected to a projector only the two "Display" and "Color" tabs appear.
4. Click the middle tab and near the bottom of the tab window you will see a check box to enable mirroring. If it is a projector that Mountain Lion doesn't know about yet, it will be uncheked by default.
5. Once the mirroring check box is checked, close System Preferences, and mirroring should now work. If not take the adapter out and re-insert it. If that doesn't work, reboot your computer.
Following these steps should have the projector mirroring your desktop on the projector as normal and since Mountain Lion remembers the setting to be for mirroring for the new projector, it will automatically mirror the desktop next time you connect to this same projector without having to do the above.
I can confirm this works, as I went to university today and used the same projector in the lecture theater I normally do. When I connected the Mac to this projector, the computer switched to mirroring mode without me having to do anything.
Then I tried a different portable projector and the problem you described occurred. I followed the steps above and mirroring was enabled. Then, just to make sure this had not messed up the settings for projector I normally use, I went back to the lecture room, connected the projector and it went into mirror mode without me having to do anything. So Mountain Lion remembers each projector you set mirroring for.
I hope this information helps.
Since, this thread shows many people have the same problem, I asked support to create a new knowledge document about setting up mirroring for new VGA projectors. The request is being forwarded on to the powers to be.
If you and others reading this have the same issue, and follow the steps above, could you kindly post a reply to this comment. Apple communities in Japan is not very active. And top support told me that they monitor the discussions and if there many people having the same issue, they get their engineers working on it. I want to contact support again and provide them with a link to your replys so that the engineers on the Japan side can convince their bosses to write a knowledge based note which is made available in all languages.
I have been able o connect to a projector but the mirror mode only seems to work in powerpoint when I click on the mirror button in powerpoint. Is there a way to mirror the screen when not in powerpoint?
Please have a read of my post which is at the end, or near the end, of this thread and let me know if it helps.
Apologies for all the spelling errors in the post, I was typing the solution when half asleep!
Thanks very much for this very detailed response.
I'll try this next time I have to use the projector. I have used the projector a few times and have to say that I like the fact that it doesn't "mirror" the raw display until I select "slideshow". It allows me to navigate through different screens looking for different presentations or files and the audience can't see my files.
I will try your suggestion next time and see how I go.