This demo shows an interactive paper system called MixPad, which features using mice and keyboards to enhance the conventional pen-finger-gesture based interaction with paper documents. Similar to many interactive paper systems, MixPad adopts a mobile camera-projector unit to recognize paper documents, detect pen and finger gestures and provide visual feedback. Unlike these systems, MixPad allows using mice and keyboards to help users interact with fine-grained document content on paper (e.g. individual words and user-defined arbitrary regions), and to facilitate cross-media operations. For instance, to copy a document segment from paper to a laptop, one first points a finger of her non-dominant hand to the segment roughly, and then uses a mouse in her dominant hand to refine the selection and drag it to the laptop; she can also type text as a detailed comment on a paper document. This novel interaction paradigm combines the advantages of mice, keyboards, pens and fingers, and therefore enables rich digital functions on paper.