During a recent episode of Hypercritical, host John Siracusa mentioned that he had received feedback from readers of his OS X Mountain Lion review commenting about the failings of full screen mode in Mountain Lion (and previously in Lion), particularly with respect to multiple monitor support.

I see where these comments have come from and have sympathy. When I first installed Lion I was eager to get stuck into this new world of full screen apps. Pressing the little button on the title bar unleashed a magical zoom animation. Some apps just stretched the existing interface, but others (such as iPhoto) changed their interface to better suit the full screen experience. It was very exciting for about 5 minutes, but it wasn’t long before I shared the frustrations aired by Siracusa and his readers:

No, I wanna use the other screens, I wanna put stuff there, I wanna see my other windows there, I wanna see my web browser there, my Twitter feed there - whatever the heck I have over there. And you can put palettes and stuff from the application that you made go full screen, you can put them on the other screens but you can’t use them for other applications. It was like, it was almost like it was being mean to you, it’s like “I know you want to see your Twitter client, but I’m putting linen over that whole screen - nah!” and that pissed people off.

I admit that I was that reader initially and I found the lack of flexibility when using multiple displays was exceptionally frustrating. The app running in full screen mode would take over the primary display but the secondary display would only contain that boring linen background. Yes, it was possible to place extra palettes or inspectors on the secondary display but there didn’t seem to be any way to truly take advantage of the additional real estate.

It sure would have been nice if users could have placed two independent apps side-by-side. Or if developers could have created UI layouts that took advantage of full screen mode with multiple displays, akin to the way full screen editing was available in many previous versions of Aperture. John, being the sensible guy that he is, tried to reason it out, and I think he almost nailed it¹ when he said that full screen is for people who need to concentrate.

One use case I think he glossed over though is the fact that full screen is also for people who are working on portable machines. People who are working on one (possible small) screen and need to squeeze every last pixel out of their displays. It’s not for the power user who wants to work with multiple apps at once (or with a multitude of windows/palettes/inspectors from a single app). That’s what regular OS X is for and has been all along.