An EHLLAPI application can be connected to multiple presentation
space windows at the same time. The application can go back and forth
between the connected presentation space windows without having to
disconnect. For example, if an application is connected to presentation
space windows A, B, and C, the application can access all of A, B,
and C at the same time, and the other applications cannot access A,
B, or C.
A Connect Window Services function is sufficient
for the process. However, each thread that requests a Connect
Window Services must have a corresponding Disconnect
Window Services (102), or one of the threads must issue a Reset System (21), which affects all threads and
disconnects any remaining connections.