supersleuth – See below for an extract from the NSW Government Registrar General’s Guidelines which should answer your questions. My understanding is that the windows that you are referring to would now be classified as common property unless the building plan has a note on the plan saying otherwise. Therefore the window locks on your apartment would be the responsibility of the OC.
“Pre 1974 plans
The original legislation provided that the boundary between separate lots or between lots and common property was the centreline of the dividing structures being walls, floors or ceilings. Upon the commencement of the new legislation on 1 July 1974 these boundaries, for previously registered plans, moved to the inner face of the walls, the upper surface of the floors and the lower surface of the ceilings. The structure then became common property. Any walls or other structure which are between separate parts of the same lot remain as part of the lot and are not common property. This occurs even if the structure is shown on the plan. The most common example where these provisions create an issue is the wall within a lot between the living area and a balcony; in this case the wall and any door or window will remain as part of the lot and not become common property.
In some circumstances the plan may show a note indicating that the boundary is the centre (or face) of a structure. In this case the boundary remains in that position and is not relocated as described above.
With regard to plans registered prior to 1 July 1974:
- Any structures between separate parts of the same lot are part of the lot and are not common property.
- A structure between separate lots or between a lot and common property is common property.
- If the plan described by a note the location of a boundary relative to structure the boundary was not relocated.
Careful consideration should be given to any actions involving plans prepared prior to 1 July 1974.”
(My underlining is for emphasis only and does not form part of the original document).