[1.15+] timeout in a batch script instantly exits a defterm window

[zadjii-msft]

Oh god this is so much worse in 1.15. It doesn't timeout at all, it instantly exits!

echo foo
@rem set /p id=Enter ID: 
timeout /t 10
echo bar
exit 1234

Originally posted by @zadjii-msft in #12951 (comment)

[zadjii-msft]

OH oh oh I bet this has to do with focus events. That's my guess - timeout will bail on input. Like, any input? That I'm not sure about. But I bet the regression between 1.12 when this was filed, and now (1.15/16/17) is the focus event stuff, and I bet eveything is immediately getting a focus event in the input queue right off the bat.

I'll need to go inspect timeout's source to confirm. That's my hypothesis.

Notably, this doesn't repro the same if you actually "restart" the batch script, until you press a key:

I noticed this when I restored the Terminal from being quit, and this defterm window came back (presumably, without the focus event). This might be related to #13514

Okay, my hypothesis was wrong. Looks like timeout does filter FOCUS events out... even if it does have some other horrifying code in it.

[zadjii-msft]

Uh, this looks fixed. At least in 1.19.whatever.this.selfhost.build.is