System Information
OSX 10.9 Mavericks, MacBook Pro 13.3" 2.6 Ghz, 8GB RAM
Blender Version
Broken: 2.6.9.0, r60991
Worked: (unknown)
After starting Blender 2.6.9 on my MacBook Pro on the primary desktop I select full screen mode. That works fine. I use the trackpad to swipe to the right and arrive at my Dashboard space. I then swipe left to get back to Blender. Blender appears, but it loses full screen mode because the Dock is brought to the front.
I experimented a little bit with the left/right swipe and noticed that after the trackpad swipe OSX brings the current application to the front even if no current application is selected (clicked in the background). Could it be that Blender is somehow not making itself current, so OSX selects Dock which is probably the last application since that's how I launched it.