Mousetrap is a third-party plugin, and is not maintained by the OpenSesame team.
Pascal Kieslich and Felix Henninger have developed the mousetrap plugins for OpenSesame (Kieslich & Henninger, 2017). These plugins allow you to track the movement of the mouse cursor, which has been used to investigate the time course of cognitive processes in many psychological domains (Freeman, Dale, & Farmer, 2011).
Mousetrap offers two plugins for mouse tracking in OpenSesame that can be included in the experiment via drag-and-drop. The mousetrap response plugin tracks mouse movements while another stimulus (e.g., a sketchpad) is shown, analogous to a keyboard or mouse response item. The mousetrap form plugin allows for tracking of mouse movements in custom forms. Besides, both plugins also provide Python classes, which can be used in Python inline scripts for maximum customizability.
Once data have been collected with the plugins, the data can be processed, analyzed and visualized using the mousetrap R package.