Warning! Spoilers! This is for a fanfic, so please answer as best you can.
In the Day of Black SunPart 1 episode, we occasionally see Zuko's bedroom, with his bed having an entire wooden canopy over it, the part over the foot having a huge circular appearance, and two windows on the left. When he leaves his bedroom, he walks out of a metal "doorway" into what looks like a long hallway, although the bedroom's opening doesn't exactly have a door to close, and (if you look closely) there is another doorway "structure" between the metal one and the hallway. In the comic The Promise Part 1, we see more of his bedroom, and it seems basically the same, at least when referring to the bed, windows, and the place of the "doorway". When Kori tries to murder him, there doesn't, once again, seem to be a door to his bedroom; instead just another open "entryway" and another long hallway through it, where he and Kori fight. However, the entryway/opening seems to be rather long for what would be his "doorway".
Is this the same bedroom before he became Fire Lord and was just the "returned-home now honored again" prince? In the comic, the guards mention that they moved him into the safest tower in the palace, and although they could have just moved his bed, furniture, etc. to a different room, it mainly appears to be the same one, especially because of the windows in the same place. We don't see whether or not if there is that metal "doorway" that was inside his prince bedroom also in his Fire Lord bedroom, since we only see the opening between the end of his Fire Lord room and the hallway in the first scene of it, as he yells at his guards, and one of the ending scenes, when he exits the "hall" connecting his room to the actual hallway, with no doorway seen and looking like he went through a rather long corridor to get to the Kyoshi Warriors now stationed at the beginning of the hallway.
Also, why wouldn't his bedroom have a door, whether as the prince or Fire Lord? It seems interesting that as king, he goes through a big enough "hall" to get to the actual hallway past the Fire Lord's bedroom, and we never see an actual door. Sure, we see his guards, who become the Kyoshi Warriors, at the start of the hallway and the end of his "doorway", but why isn't there any real door?! That seems really weird to me, since he should at least have some more "protection" in case an attacker tries to barge in again and gets through his guards, like Kori did. Do you think there is an actual door between his room's real entryway and the corridor that leads to the hallway, and we just haven't seen it (yet)? Or do you think that there isn't a door between his room's end and its "hall" so that if there is trouble, his guards can easily run to his room to protect him?