Sketch - Window

In the building where we live there is a courtyard which we can look onto from our kitchen window. We can see our neighbours windows on the other side of the courtyard. One window in particular fascinates me because one of their plants has crept up and out the open window and a a single red flower has blossomed.

I had an idea to sketch this, then put the sketch in a letter and deliver it to the occupants of this flat, with a note telling them how nice I think their plants are, and where I lived. I'm curious to how they would respond.