Four-leaf sliding door gives a bigger opening space than three-leaf sliding door.
Glass on the door that comes in panel is meant to reduce the risk when it breaks i.e the glass won't fall in one big piece.
Subframe for the outer frame of sliding door is getting popular. Instead of having the outer frame embedded, subframe is used and the outer frame will be screwed onto the embedded subframe.
In this way, the door and window frames are installed only when the house is ready for occupation and after all the paint work is done. When the house owner decides to change to different types / design of window and door in the future, there is no need for hacking to replace the outer frames.
