Paul is an interesting "case" because while he is like many adolescents who rebel, Paul simply can't stand to go along with the provincial life that he is forced to accept. Consequently, he reinvents himself by making up stories of his connections with the theater and its inhabitants. Paul does not intend to become an actor or a part of the theater. He simply wants to dwell in its atmosphere. Paul's inventions are like the theater's performances: staged, creative, and in many cases so unrealistic as to be escapes from reality (like fairy tales). So, Paul is drawn to the romance of this escape. He flees to New York when this escape is taken from him.
Paul steals money to live luxuriously if only for a few days. Here we see that Paul's concept of an ideal life becomes conflated with wealth. And although Paul's concept of this wealthy, artificial paradise is flawed because of its superficiality, it is still paradise to Paul. He sees in the theater and in the world of the wealthy something more beautiful than the mundane world of Cordelia Street. When this is taken from him, Paul sees no escape other than death.
Paul was always looking for an escape. It is the sense of looking that relates to Paul's dream of being, and therefore looking, somewhere other than where he was. It's as if he were always looking through a window to some other place. After the performance, Paul followed the soprano to her hotel, watched her walk in, and began to daydream that he was with her. When he snaps out of his daydream, he is left with a dichotomy: the rain-soaked, dreary world he is standing in and the "orange glow of the windows above him." What dwelt behind that window was another fantasy, the escape Paul longed for.
There it was, what he wanted--tangibly before him, like the fairy world of a Christmas pantomime--but mocking spirits stood guard at the doors, and, as the rain beat in his face, Paul wondered whether he were destined always to shiver in the black night outside, looking up at it.
Paul goes home and decides that in order to avoid his father's disapproval, he will wait in the basement. He uses a window to get in the basement. Again, the window is a means of escape and avoiding his reality.
When Paul is walking around Central Park, he notices the "avenue stages" (window displays). Particularly striking to him are the flowers enclosed in glass, untouched by the cold and snow outside. Throughout this story, flowers are a symbol of the vitality of life Paul strives to seek:
Here and there on the corners were stands, with whole flower gardens blooming under glass cases, against the sides of which the snowflakes stuck and melted;
In his sitting room, Paul is actually in the fantasy world. He looks out the window to note his separation from the cold reality outside, that he is protected (like the flowers in the window displays). Windows symbolize an actual and figurative border between reality and fantasy.
We might also consider the front of the theater's stage (fourth wall) as a window between the audience and the world of fiction/performance.