Question: how does `VK_KHR_present_wait` interacts with DPMS?

I am asking because over here in Xorg/GL land the somewhat analogous (but much less powerful) APIs, e.g. `glXWaitVideoSyncSGI`, or the Xorg Present extension, tend to misbehave when the monitor is turned off by DPMS. Depends on the drivers used we see events with duplicate MSCs, applications entering a busy loop, or other kinds of problems.

`VK_KHR_present_wait` specifies that presentation is only complete when the user sees the first pixel, which implies that if a present is initiated just before the monitor is turned off, it will only complete after the monitor is turned back on, which can be indefinitely far into the future. I just want to get a clarification whether that's indeed the case.

Thanks!

Start by reviewing the VK_KHR_present_wait specification and the DPMS behavior described in the issue, then compare the cited glXWaitVideoSyncSGI and Xorg Present cases. Determine how presentation completion should behave when the monitor is powered off, and document a clear clarification in the Vulkan specification.

Written by the indexing model from the issue text.