You know that SciTE quality to show how many instances of it is running and what is current one that you view. Information about this is in SciTE window title. Something like: "path\name - SciTE [2 of 7]" I find that very useful an wanted to implement that in one of my script. This is the idea and the procedure: 1. When script starts call function CreateSemaphore from kernel32.dll. Use unique string (GUID) 2. Call ReleaseSemaphore function from kernel32 to increas the count of the semaphore ob