Slightly OT, but historically graphic displays have always been rendered by hardware with (0,0) at top left. This precedes pixel graphics, it goes back to character generators (e.g. MC6845). Probably makes sense for character displays which are read top down.
I think it is coincidence that the CRT scanlines also proceed top down. If the refresh rate is high then is shouldn’t matter, although the very first TV systems used some very slow scan rates. But even the original mechanical TV with a scanning “Nipkow” disc had a hole pattern that scanned top down.
There is no particularly good reason that applications written in the past 30 years should not fix the axis, it saves a small calculation when drawing which is nearly insignificant. Every PC application I wrote since the start of Windows (3.1) I have always put the Y axis to match a “normal” XY layout. All modern window managers seem to allow custom transforms, so it is almost transparent to application code.
History aside… I tried to find the spec for the new library format but failed, I am sure Wayne posted a link to it on the dev list. Anyone have a link ?