[SteamVR] Overlay closes main app (t.headset.overlay)

[Python1320]

Opening any VR app in SteamVR and launching the following seems to close the original app no matter what:
conf.lua

function lovr.conf(t)
    t.headset.overlay = true
end

main.lua

function lovr.draw(pass)
    pass:cube(0, 1.7, -1, .5, lovr.headset.getTime(), 0, 1, 0, 'line')
end

Development appears to have stalled on OpenXR overlays in favour of API layers it seems.

It also seems there is no LÖVR pre-built with both overlay and SteamVR, which is a shame, since there it probably works.

OpenXR has API layers seems to be the current supported option: "OpenKneeboard currently supports overlays with: OpenXR Direct3D 11 games, via a custom API layer" (unfortunately licenses are not compatible with LÖVR).

Related:

• https://github.com/mbucchia/OpenXR-Layer-Template/wiki/Tutorial-1:-Your-first-OpenXR-API-layer
• https://github.com/mbucchia/OpenXR-Layer-Template
• Allow SteamVR Unity Plugin to run in "Standalone" mode without Unity XR enabled ValveSoftware/steamvr_unity_plugin#336
• Support overlay mode? ValveSoftware/steamvr_unity_plugin#108 (comment)
• https://github.com/LunarG/OpenXR-OverlayLayer#implementation-specifics
• Can't build xr_extx_overlay project LunarG/OpenXR-OverlayLayer#31 (comment)

[bjornbytes]

This is currently the intended behavior. t.headset.overlay turns your app into an OpenXR overlay, and SteamVR does not support OpenXR overlays.

API layers automatically work with any OpenXR runtime/application, including LÖVR. I currently use API layers to add Ultraleap hand tracking to LÖVR, for example.

To get overlay functionality on SteamVR, we're basically either waiting on SteamVR to add support for XR_EXTX_overlay (unlikely), or for the OpenXR working group to release better overlay extensions and SteamVR to add support for those. Until then, XR_EXTX_overlay is the best way to do it. To my knowledge it only works on monado and other monado-based runtimes.