I cannot believe this happened. I was toying around with my display settings (resolution). When I reopened iPhoto, I noticed that I the app opens up in the upper right corner of my screen so that only 25% of the window is available to me. I cannot drag the window back into view, because you can only do this from the top bar (which I cannot even see). I tried playing with resolutions, but iPhoto just scales bigger or smaller, never leaving the corner. This sucks.
