Can you explain us the difrerence between reverse enginerring Long _HTCTI(int param1) and Long _HTCTI(int WindowPosition) ?

An API is an API and it will be the same if it is reverse engineered or copied the declaration.

And Google didn't copied without permission Sun's code, they used Apache Harmony

Incorrect. Wine is based on Windows documentation of Windows APIs. There is no practical way to "discover" an API.

Still incorrect. The black box testing refers to testing of the implementation, not the API.