I don't think putting a door in a doorframe that used to have a door would count as structural changes but I don't know anything about anything at all.
Damn your chalkboard drawings are so neat O_O
I want one of those in my house, we could use an extra bookshelf XD Even got a doorframe to put one in though we took the door that was in it out for reasons and I can see more accidents happening if we put a heavier one there x_x