Cancelling a stdin.read?

[Lass Safin via Digitalmars-d-learn]

On Sunday, 10 April 2016 at 18:00:31 UTC, hilop wrote:
> On Sunday, 10 April 2016 at 08:29:22 UTC, Lass Safin wrote:
>>
>> I have a multi-threaded program, one thread drawing to a 
>> window and handling it, the other handling stdin.
>>
>> [...]
>
> The external program that writes to the input has to close it 
> when it has finished to write.

I'm writing from my terminal, and I have my graphical window 
opened beside it.
I want to close the input from not an external program, but 
rather from within.