If the foreground app enters a compute-intensive eternal loop, you're screwed.

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I'll be doing some more development on this in the next couple of days, most importantly adding in the feature that will prevent 2 copies of Sparky8 running at the same time.

_mutex_name db 'Sparky8 is already here',0
    

invoke  CreateMutex,NULL,FALSE,_mutex_name
invoke  GetLastError
cmp     ax,ERROR_ALREADY_EXISTS
je      exit
    

invoke  CreateMutex,NULL,FALSE,_mutex_name 
test eax, eax
jne okay
invoke  GetLastError 
cmp     eax,ERROR_ALREADY_EXISTS 
je      exit
jmp other_error
okay:    

Return Values

If the function succeeds, the return value is a handle to the mutex object. If the named mutex object existed before the function call, the GetLastError function returns ERROR_ALREADY_EXISTS. Otherwise, GetLastError returns zero.
If the function fails, the return value is NULL. To get extended error information, call GetLastError.

invoke  CreateMutex,NULL,FALSE,_mutex_name 
invoke  GetLastError 
test    eax, eax 
jnz     exit     

2. CreateMutex can fail for other reasons than ERROR_ALREADY_EXISTS, you should always think of this

Quote:

CreateMutex can fail for other reasons than ERROR_ALREADY_EXISTS, you should always think of this

Example maybe?

However, if the caller has limited access rights, the function will fail with ERROR_ACCESS_DENIED and the caller should use the OpenMutex function.

So if you know how other error check(s) would be useful here, i'm all ears

Return Values

If the function succeeds, the return value is a handle to the mutex object. If the named mutex object existed before the function call, the GetLastError function returns ERROR_ALREADY_EXISTS. Otherwise, GetLastError returns zero.
If the function fails, the return value is NULL. To get extended error information, call GetLastError.

On success -> retVal = handle; lastError = {0, ERROR_ALREADY_EXISTS}
On failure -> retVal = NULL; lastError = {1..ERROR_ALREADY_EXISTS-1, ERROR_ALREADY_EXISTS+1..$FFFFFFFF}