Common OpenXR misconceptions

[actually_fred]

Most of the replies in help threads contain factually incorrect advice, which makes setting up VR more confusing for everyone. I'm going to address a few common ones:

- SteamVR + OpenXR: SteamVR supports OpenXR (it's an "OpenXR runtime") - if you want to use SteamVR + DCS, you want to start by setting SteamVR as your OpenXR runtime. You do not want to 'disable OpenXR' to use SteamVR, unless for some very rare reason you specifically want to use OpenVR. If you do this, no games that require OpenXR will work unless you change your settings back.
- "OpenXR Tools for Windows Mixed Reality" is specifically for Windows Mixed Reality headsets. If you have a quest, rift, pimax, varjo, beyond, or any other non-WMR headset, do not install this software, and especially do not click the button to set WMR as your OpenXR runtime. If the tutorial you're watching or the guide or reading says to do this and doesn't say "just for G2" or "just for WMR", find a better guide. If you just want to see information on openxr, https://github.com/maluoi/openxr-explorer/releases/latest is a better tool, in combination with https://github.com/fredemmott/OpenXR-API-Layers-GUI/releases/latest if you have several OpenXR API layers (roughly 'plugins') installed*. 
- "OpenXR Toolkit" is not the same thing as "OpenXR Tools for Windows Mixed Reality"
- "OpenXR Toolkit" is not the same thing as "OpenXR"
- "OpenXR Toolkit" is never required. It's a great tool, install it if there's a specific reason you want it, but it's not necessary.
- "Set WMR/your headset/SteamVR to OpenXR": this is the wrong way around and can confuse people: "Set OpenXR to SteamVR/WMR/your headset" is correct. It's a single OpenXR setting for all OpenXR hardware manufacturers and games - you are changing if OpenXR games use WMR, oculus, steamvr, or whatever, not a headset setting. Specifically these buttons in steamvr/wmr/manufacturer-specific stuff all change `HKEY_LOCAL_MACHINE\SOFTWARE\Khronos\OpenXR\1\ActiveRuntime`
  - SteamVR can simultaneously be your selected OpenVR and OpenXR runtime. Games will only use one at a time.
  - If WMR is set as your OpenXR runtime, your G2 can be used by openxr *or* steamvr-via-openvr *or* classic (deprecated) Windows Holographic *or* opencomposite-via-openvr* without any settings changes. Games will only use one at a time.
  - If Oculus is set as your OpenXR runtime, your quest/rift can be used by openxr, *or* steamvr-via-openvr *or* opencomposite-via-openvr *or* the classic (deprecated) libovr without any settings changes. Games will only use one at a time.
  - If you need to change your OpenXR runtime and the buttons in the various vendor-specific tools aren't doing what you want, https://github.com/rpavlik/xr-picker/releases/latest is a good tool

* OpenXR-API-Layers-GUI can also be used to fix issues, but I'm recommending it here because layer (plugin) order matters, and the current version of OpenXR-Explorer sorts them alphabetically - this means that OpenXR-Explorer is not currently useful for troubleshooting API layer issues. This should be fixed in the next version of OpenXR-Explorer.

Edited January 5 by actually_fred
Added OpenXR Toolkit != OpenXR