It is normal, I have seen and fitted doors like this before.
The low threshold runs right through so that the frame can be made in one piece, Otherwise you would have to have separate door and window frames. The glass panel is already quite narrow so this would have meant making the door about 100mm narrower (70mm frame + coupler). This may also have ment that the panel would not fit in the door or at least look odd as the moldings would nearly be touching the frame.
Looks like a Liniar door, Maybe thats why I recognize this set up and the others don't.
The door may have just been wound up a bit too far as the corners seem to line up nicely.
One thing I did notice in the 1st pic is a little molded plastic bit seems to be missing. Right hand side is showing white
The low threshold runs right through so that the frame can be made in one piece, Otherwise you would have to have separate door and window frames. The glass panel is already quite narrow so this would have meant making the door about 100mm narrower (70mm frame + coupler). This may also have ment that the panel would not fit in the door or at least look odd as the moldings would nearly be touching the frame.
Looks like a Liniar door, Maybe thats why I recognize this set up and the others don't.
The door may have just been wound up a bit too far as the corners seem to line up nicely.
One thing I did notice in the 1st pic is a little molded plastic bit seems to be missing. Right hand side is showing white