On both my Mac Pro and my iMac, I've run into a problem where the iPhoto library simply doesn't show up in the Desktop & Screen Saver System Preferences panel (in Mac OS X 10.6.x). Well, sometimes it shows up, but simply as a line reading iPhoto, but without any actual content.
When this happened the first time, I looked in Console and found the following entry for each time I'd tried to load the Desktop tab of the Desktop & Screen Saver panel (reformatted for easier reading):
Googling on that error led to a number of pages, including iLife: Cannot See iPhoto Files in Other iLife Applications on Apple's support site. But after trying everything in that article, I still couldn't see my iPhoto images when trying to set the Desktop picture.
I even tried deleting all cache files, rebooting, and (a very time consuming process) rebuilding the iPhoto library. Nothing fixed the problem. (This seems to be related to the size of the iPhoto library; I've only ever seen the issue on my main Mac, which has over 25,000 photos and videos, using 235GB of drive space.)
The workaround: While I still haven't solved the problem (as it seems to be a bug in OS X itself), there is a workaround. As posted by mrkgoo in this thread on Apple's Discussion site, here's what to do:
- Open the Desktop & Screen Saver panel in System Preferences.
- Click on the Screen Saver tab. You probably won't see iPhoto listed here, but just wait—potentially quite a while, but keep waiting. Eventually, you will see a fully-functional iPhoto entry.
- Click on the Desktop tab, and bingo, notice you now have an iPhoto entry there, too.
- Choose the album you want to use for the images on each connected monitor.
- Click back to the Screen Saver tab—if you don't, then you'll have to repeat this process the next time you open the Desktop & Screen Saver System Preferences panel.
While this is moderately annoying, it definitely works. I'm documenting it here because I forget the solution every time I decide to change my set of desktop images. (I've also submitted this to Mac OS X Hints, so it should show up there at some point.)
Why does the workaround work? I'm not sure, but to my non-technical eye, it seems that the Desktop tab has a short timeout for loading the iPhoto library, while the Screen Saver tab has no such limit. Once the data's been read in, though, the Desktop tab is quite willing to display and use it.