[3.x] Flickering with "Fullscreen" enabled and dual monitors

[Torguen]

Tested versions

v3.7.dev.custom_build [5155fe5]

System information

w11 - nvidia GTX 1650

Issue description

In this video, you can see the constant flickering that occurs on the monitor where Godot is set to fullscreen.
Every time the cursor moves from one monitor to the other, flickering happens on the monitor that contains Godot in fullscreen mode.
Occasionally, flickering also occurs when running or stopping the project.

I have one Full HD monitor and another one with a resolution of 1440x900.

2025-06-05.11-44-31.mp4

Steps to reproduce

With two monitors, set Godot to fullscreen and move the cursor from one monitor to the other.

Minimal reproduction project (MRP)

...

[lawnjelly]

This seems unlikely to be an issue with Godot 3.x (but not impossible), essentially we just render to opengl and swap buffers afaik.

A quick google search reveals loads of results for flickering with dual monitors with Nvidia.
https://www.google.com/search?q=nvidia+flickering+dual+monitors

As well as Godot, it can be e.g:

• a driver issue
• a GPU hardware issue
• monitor issue
• OS issue

It sounds like playing with your nvidia settings may well give some joy.

[Torguen]

This doesn't happen in Godot 4.5 dev 5.
I haven't been able to fix it by tweaking the NVIDIA control panel settings... though there's not much to tweak there anyway.
I guess it's better not to use fullscreen mode.

[lawnjelly]

I eat my words, it could be a peculiarity of windows, could be the same bug as this: #104686

Unfortunately I can't look at this as I don't have any windows machines.

Do you have anything like an auto hide task bar by any chance? It's possible some windows widget is interfering with fullscreen.

[AThousandShips]

To confirm it doesn't happen in 4.5 dev 5 with compatibility?

[Torguen]

With compatibility mode, it also works without issues.

[bruvzg]

Every time the cursor moves from one monitor to the other, flickering happens on the monitor that contains Godot in fullscreen mode.

This is pretty usual for exclusive full-screen, specific behavior depends on the renderer and GPU drivers a lot. Making borderless window with the size of a screen won't help, since drivers almost will always force it to exclusive mode as well.

In 4.x there's a dedicated non-exclusive fullscreen mode (MODE_FULLSCREEN - used by editor, MODE_EXCLUSIVE_FULLSCREEN is equivalent of 3.x fullscreen) specifically to allow interactions outside the full-screen window.

[KeyboardDanni]

My humble opinion is that defeating direct scanout should only be done as a last resort because going through the compositor is likely to introduce jitter/stutter. It also might not even work on Windows 11 due to improvements to windowed optimizations.

Questions for OP:

• Is MPO enabled or disabled in driver settings?
• Is there a mismatch between the displays in terms of DPI scaling, refresh rate, or G-Sync/FreeSync availability?
• In the nVidia Control Panel, is "Vulkan/OpenGL present method" set to "Prefer native" or "Prefer layered on DXGI Swapchain"?