CHR_TRN is normally buffered to SNES WRAM, and only gets transferred during a PCT_TRN. However, the transfer point is when the border finishes fading (so the transfer is seamless), so it's actually possible to send PCT_TRN, then CHR_TRN during the fade, and have it work.

Alfred Chicken apparently relies on this.

• Investigate timing window

  Document all this
  To pick up a draggable item, press the space bar. While dragging, use the arrow keys to move the item. Press space again to drop the item in its new position, or press escape to cancel.

Note that this also means the border tiles do NOT update immediately upon CHR_TRN!