Triggering a user event in PB window form another process

Hello, all

Is it possible to trigger a custom event with a string parameter in a window from another process?

Assuming the calling process has the window handle, which system message must it invoke in order to trigger a user event on the called window with a string parameter?

I know how to click a button on a window, and how to launch a custom event with a numeric parameters, but I do not know how to trigger a user event with a string parameter.

Does anyone have an example of such messaging?

Thank you

Arcady