If you want an entity to interact with mouse events, add the Mouse component. It will then be passed the standard DOM-style mouse events: "MouseDown", "Click", etc. (Note the capitalization.)
- Entities in a DOM layer will directly use the native DOM events
- Crafty implements picking in other layers using the entity's MBR
- An entity with the collision component will use its hitbox instead of the MBR
- You can override these behaviors by providing a polygon specifying the clickable area; see the documentation for details
See also the Draggable component.