Just outside the window

Heaven and Hell await. At first, I thought this might be an altarpiece, but there is an enshrined altarpiece elsewhere in the room. This is clearly a window revealing two different potential destinies.

Livre d’heures, en latin et en français, à l’usage de Cambray
Source: gallica.bnf.fr
Bibliothèque de l’Arsenal, Ms-1185 réserve, fol. 373v.