Thanks for your suggestion. I already found my problem. It was kind a dumb mistake but now it is fixed 🙂
Thanks Tyler!

What about if you pop your window out (see the window API sample, specifically the call to XPLMSetWindowPositioningMode(in_window_id, xplm_WindowPopOut, 0))? My hypothesis here is that your code isn’t drawing correctly with respect to the window bounds; popping the window out will change the coordinate space for drawing in a similar way to VR.

If popping the window out works okay, I’d say get me a minimal reproducible example plugin that has this issue and I can look into it. (You can either post it here, or email me at my first name at X-Plane.com.)

I added a function called “draw_HMD” and called it inside the “draw” function. So it should be in the callback.
When it still is on my monitor (before pressing Toggle VR), my speed is shown correctly and is refreshed each gametick.

This drawing is taking place from within a window’s draw callback?

Widget windows can be opted in to “modern” windowing features like support for UI scaling and being popped out into a native OS window (see this note). But if you’re asking about styling windows to match X-Plane 11 text, buttons, etc., we don’t have a good solution right now. The backstory here is: between X-Plane 10 and 11, the back-end infrastructure for our internal GUI framework changed entirely, in a way that no longer matches the public widgets API at all. So long term, we need to either:

• deprecate the existing API and create an entirely new one that more closely aligns with the internal GUI framework, or
• bbbbbasically back-port all our new GUI components to the old system.

The cost for either is measured in months of dev time, and we just haven’t had the resources to devote to it yet. :/

Thanks for the reply. I noticed that the Widgets API does not include the current, modern GUI elements (or maybe I did something wrong). Is it planned to expose those via the Widgets API at any time in future?

You can use any valid OpenGL drawing technique you want. The point of the example is to show you how to interact with X-Plane, _not_ to teach you how to use OpenGL. The OpenGL code shown isn’t even useful, it is meant to prove that user-based drawing is working with a minimal sample.