a lil speculation: behind tifa is everything green... like the life stream... this art may be refering to the time tifa and cloud fell into the life stream and tifa saw bits and pieces about clouds REAL past... the rocking chair may be a referance to Nifelheim, their old home, while the glass hindering her to enter, showing that she can see the past, but not change it... if anyone needs a plausible explanation you can use my asumption until something more plausible is released ^^