Abstract : The recent graphical rendering models of desktop computers can be used to explore new window management techniques. In order to evaluate these new techniques, we should have tools that help us better understand how users manipulate their windows. We present a log and visualization tool of the Human-Window interaction for the X Window system. The tool allows to replay a session (without the windows contents) as a video. A filtering system allows to select and easily access high level actions. We give some examples of application of this system.