How to find the running program and send some message to it?

[kin2pete]

-Use the System.Diagnostics.Process class to get a list of running processes by name, handle, or window handle. Or if you prefer, inspect all window titles to find your process.

-Look out to catch System.Diagnostics.Win32Exception

-Determine which instance of your program to send messages to by inspecting the process start time. (Check the 'Ticks' property of DateTime. That should be more accurate)

-Use Process.CloseMainWindow() or Process.Kill() to exit whichever instance you need to exit.