When completely absorbed in a meaningful task, a friend or stranger passes by and says "Hello" or initiates a conversation. I now find myself not being as kind as I would like to be as my mind is still completely absorbed in the task at hand.

Meditation has helped improve my ability to focus like this and let external events just flow by, but from a Buddhist perspective, how can I practice my ability to "switch" and be more present in the interaction with the by-passer when I actually want to?