As it was an interesting challenge, here is an example of how to do it.

This takes Rads method a little further, to cater for the wrinkles I've talked about in the previous post.

The process finds all the active NTDVM process headers, and then identifies all the threads in the processes.

It then starts the Win16 application, and checks for all the threads again, recording any new ones.

Finally, it monitors the "new" threads, and exits with a message when one of them closes.

If you need to keep an application running, just use this and restart when it closes.
If you need to check whether the application is already running, then use this technique to record the thread details in the registry or an ini file after you start the application.
When you next try to start the application, use the saved settings to check whether the process is still running or not.

Code:

Break ON
   
$=SetOption("Explicit","ON")
$=SetOption("WrapAtEOL","ON")
$=SetOption("ASCII","ON")
   
Dim $sExePath
Dim $aiExistThreads, $aiNewThreads
Dim $iThread
Dim $sThreadList
Dim $iCheckInterval
   
Global $oWMIService
   
$iCheckInterval=3					; How often do we check if application is still active
$sExePath="C:\Program Files\JETFRM41\JFDESIGN.EXE"	; What is the application to run?
   
$oWMIService = GetObject("winmgmts:\\.\root\cimv2")
If @ERROR "Cannot access WMI sevrice, error is " @ERROR ": " @SERROR ?  Exit @ERROR EndIf
   
$aiExistThreads=GetThreadHandles(GetProcessList('Where Caption="NTVDM.EXE"'))
Run $sExePath
Sleep 1
$aiNewThreads=GetThreadHandles(GetProcessList('Where Caption="NTVDM.EXE"'))
   
$sThreadList=""
For Each $iThread in $aiNewThreads
   "Checking "+$iThread+":  "
   If $iThread
   	If (AScan($aiExistThreads,$iThread)+1)
		"Existing thread" ?
	Else
		"New thread" ?
		$sThreadList=$sThreadList+","+$iThread
   	EndIf
   EndIf
Next
   
If $sThreadList
	Dim $aiThreads
	Dim $colThread, $oThread
	Dim $i, $bThreadRunning
	$sThreadList=SubStr($sThreadList,2)
	$aiThreads=Split($sThreadList,",")
	? "Monitoring application threads: "+$sThreadList ?
	While Not KBHit()
		For Each $iThread In $aiThreads
			$bThreadRunning=0
			@TIME+" Checking "+$iThread+" is still running "
			$colThread=$oWMIService.ExecQuery('Select Handle from Win32_Thread Where Handle="'+$iThread+'"',,48)
			For Each $oThread In $colThread $bThreadRunning=1 Next
			If $bThreadRunning
				"OK" ?
			Else
				"Stopped" ?
				? "*** APPLICATION HAS PROBABLY CLOSED ***" ?
				Exit 0
			EndIf
		Next
		Sleep $iCheckInterval
	Loop
	Get $
Else
	"**ERROR** Application failed to start, was already started (single instance only) or was too slow!" ?
EndIf
   
Exit 0
   
Function GetProcessList(Optional $sWhereClause)
	Dim $colProcess,$oProcess,$sProcessList
	$colProcess=$oWMIService.ExecQuery('Select Handle from Win32_Process '+$sWhereClause,,48)
	For Each $oProcess In $colProcess
		$sProcessList=$sProcessList+"|"+$oProcess.Handle
	Next
	$GetProcessList=Split(SubStr($sProcessList,2),"|")
EndFunction
   
Function GetThreadHandles($aiPidList)
	Dim $iPid
	Dim $colThread, $oThread, $sThreadList
   
	For Each $iPid In $aiPidList
		If $iPid
			"Checking for threads in process "+$iPid ?
			$colThread=$oWMIService.ExecQuery('Select Handle from Win32_Thread Where ProcessHandle="'+$iPid+'"',,48)
			For Each $oThread in $colThread
				"  Found thread "+$oThread.Handle ?
				$sThreadList=$sThreadList+"|"+$oThread.Handle
			Next
		EndIf
	Next
	$GetThreadHandles=Split(SubStr($sThreadList,2),"|")
EndFunction