Willisau Jazz Festival was conceived and organized by Troxler, a gifted musician himself. Troxler has created 2 or more posters a year ever since for the festival, and the posters have become as legendary as the music they promote. Two of Troxler's Willisau designs were chosen for the Museum of Modern Art's seminal show called The Modern Poster in 1988. Rejecting the humorless and rigid International Typographic Style which dominated Swiss design, Troxler instead revelled in visual puns and bold images, reminiscent of the work of Milton Glaser in the U.S. This so-called Post Modern Style brought spontaneity and surprise into the forefront of Swiss design.