Years ago, I had almost the ideal job. I had my own fair sized office with large windows and an interesting development project. Unfortunately, the development area had also been designed with "casual interaction" in mind. The design was a kind of star shape, making it very easy for anyone to be in anyone else's area within seconds. Some other members of the team took full "advantage" of this. On bad days, there would be continual interruptions all day until about 5:00 pm. Fortunately, they were also pretty flexible about working hours, and I took to planning my arrival and departure times so as to minimize "casual interaction".