Windows API - program ID's

lpdwProcessId param returns the Process ID that you need to use.

Extern "win32"
	Function EnumWindows(Callbackptr:Byte Ptr,lParam)
	Function GetWindowText(hWnd,lpString:Byte Ptr,nMaxCount) = "GetWindowTextA@12"
	Function OpenProcess% (access, handleinherit, processid)
	Function TerminateProcess% (processhandle, exitcode)
	Function CloseHandle% (Objects)
	Function GetWindowThreadProcessId(hWnd:Int,ID:Byte Ptr) = "GetWindowThreadProcessId@8"
	Function GetClassName(hWnd:Int,clString:Byte Ptr,nMaxCount:Int) = "GetClassNameA@12" 
	
End Extern

Const PROCESS_TERMINATE = $1
Const PROCESS_CREATE_THREAD = $2
Const PROCESS_VM_OPERATION = $8
Const PROCESS_VM_READ = $10
Const PROCESS_VM_WRITE = $20
Const PROCESS_DUP_HANDLE = $40
Const PROCESS_CREATE_PROCESS = $80
Const PROCESS_SET_QUOTA = $100
Const PROCESS_SET_INFORMATION = $200
Const PROCESS_QUERY_INFORMATION = $400
Const SYNCHRONIZE = 1048576
Const STANDARD_RIGHTS_REQUIRED = 983040
Const PROCESS_ALL_ACCESS = 983040
Global CharBuffer:Byte[255]

Function EnumWindowsProc(hwnd,lParam)
	Local TID:Int
	Local PID:Int
	GetWindowText(hwnd,CharBuffer,255)
	TID=GetWindowThreadProcessid(hwnd,Varptr PID)
	If String.FromCString(CharBuffer)<>"" Then
		' Skip empty process names (threads?)
		Print "PID: "+PID+"~t hWnd: "+hwnd+" ~t"+String.FromCString(CharBuffer)
	End If 
	If Instr(String.FromCString(CharBuffer),"Calculator") Then 
		Notify PID
		DebugLog KillProcess(PID) '	
	End If 

	'Return True if you want to fetch the next window, return False to tell EnumWindows to stop.
	Return True
End Function

EnumWindows(EnumWindowsProc,0)

Function KillProcess (pid)
    phandle = OpenProcess (PROCESS_TERMINATE, False, pid)
    If phandle <> 0
        If TerminateProcess (phandle, 1)
            result = 1
        EndIf
        CloseHandle (phandle)
    EndIf
    Return result
End Function

The one you was using is a Thread ID.