fn compute_extra_draws_from_total_update_rects(&mut self) {
      for full_redraw_dirty_rect in full_redraw_dirty_rects.iter() {
+         let mut undrawn_areas = vec![full_redraw_rect];
          for elem in self.compositor_state.elements.iter() {
             for visible_region in elem.drawable_rects().iter() {
                 let intersection = visible_region
                     .area_overlapping_with(full_redraw_rect)
                     .unwrap();
                 self.compositor_state
                     .queue_extra_draw(Rc::clone(&elem), intersection);
+                undrawn_areas = Self::update_occlusions(undrawn_areas, intersection);
             }
          }
      }
+     for undrawn_area in undrawn_areas.iter() {
+         self.compositor_state
+             .queue_extra_background_draw(*undrawn_area)
+     }
  }