The story of St Anthony, also known as Anthony the Great, Anthony Abbot and Anthony of the Desert, was first written down by his friend St Athanasius (Bishop of Alexandria), some time around 360AD. As the archetype of a highly ascetical school of monasticism (the so-called "Desert Fathers"), Anthony was a popular role-model for those medieval churchmen who favoured a return to a simpler kind of religious order - a movement which was about to give rise to the Fransiscan and Dominican orders).
Although this is often described as the "Window of Saint Anthony and Saint Paul", the presence of Paul the Hermit is secondary. He appears only in relation to his encounters with Anthony, who is, in narratological terms, the 'focaliser' of the narrative. For this reason I generally refer to it simply as "the Window of St Anthony".