There are so many uses for shelf brackets! These are shelf brackets, repurposed to frame a window --- what a clever idea. You could do this to define and separate spaces in the same room, too. (Say an entryway and a dining room.
Someone has not only draped a scarf valance over a pair of panels in a very innovative way but if you notice they have also "puddled" the panels on the floor. like this for a window where sheer is not fully closed.