Passing data prom one thread to another

[adam4922]

Hi,
I have created a process that's runing a thread that open some windows form, now i want that other
running threads from the same process will be able to pass data to this windows form or even close it or reopen it.

The Windows form GUI is always in use of the end users so i cant lock.
what is the best way to implement it in c# ? i would like a short example, thanks.