Window properties - how are they implemented?

Question

I am curious if there is anyone here who has inside information about the details of implementing window properties ( SetProp, GetPropetc.) in Windows.

SetProp @MSDN
GetProp @MSDN

For example, how are checks stored and performed?

Answer 1

Warning: I looked at this a long time ago, so 1) my memory may be wrong, and 2) it may be out of date, even if I remember correctly.

When I looked, I am sure that they were implemented as linked lists, and the performance was pretty bad if you had several properties for the window.