Game Windows Shrinks on Alt+Tab

[gmbhneo]

Sometimes, some games being run though steam will show the menu bar and shrink about 10-15% of the screen size when using Alt+Tab to go to another window. Games initially work fine but this only happens after using Alt+Tab to go to another window.

I tried using borderless fullscreen and fullscreen. Both show this issue.

Oh, also tested on DMS (DankMaterialShell) and Noctalia (V4 + V5). Same issue. So it seems to be an issue with Niri in general.

My Config has already been reset so it also happens on the default config.

System Information

• niri version: niri 26.04 (8ed0da4) - niri 26.04 (Wayland)

• Distro: CachyOS x86_64 - Linux 7.1.3-1-cachyos

• GPU: AMD Radeon RX 9070 XT [Discrete]

• CPU: AMD Ryzen 7 9800X3D (16) @ 4.70 GHz

[Sempyos]

Use xorg-xeyes and see if the eyes follow your mouse while over the game

[gmbhneo]

I've tried xeyes. However, it also stays behind the navbar. But, it does not have the same "shrinking" issue.

Btw, these are my game start settings: PROTON_ENABLE_WAYLAND=1 ENABLE_LAYER_MESA_ANTI_LAG=1 PROTON_FSR4_UPGRADE=1 game-performance %command% using latest cachyos proton.

[Sempyos]

I want to you to do this with your game open, the eyes will continue to follow your mouse while over the game if it is running via xwayland
https://github.com/user-attachments/assets/8b81df93-9456-45cb-bcb9-633217b73d45

[gmbhneo]

So I've tried to get this working. However, the window of the eyes is being cut off. (since the game only takes up a certain amount of the screen) The eyes move, but the game doesn't. Every time the "shrinking" is happening, it simply got stuck. The animations still play in the game and sound works fine. When I press Alt+Enter, I can control the game again but it is distorted in size. The eyes won't move when the game works.

I hope this helps.

[Sempyos]

Uh hm, I'll get back to you with something else

[gmbhneo]

Finally I was able to capture the issue.

2026-07-09_18-18-53.webm

[Sempyos]

Oki that video is perfect, judging from the way the steam notification shows in the bottom right corner the game is running via Xwayland-satellite

[bczhc]

Try adding PROTON_ENABLE_WAYLAND=1 env if you are using proton-ge or proton-etaash or proton-cachyos.

(Btw xeyes will not move its eyes when the cursor is confined (some games do this) even if the app is running via xwayland session. A more reliable alternative way to test it is to use `watch -n0 'xdotool getmouselocation'

[gmbhneo]

Well, I've fount out, using gamescope fixes the resizing. however, this brings other limitations. So it would be great if you could fix it.

PROTON_ENABLE_WAYLAND=1 is causing the same issue.

[bczhc]

Hm hard to tell it's necessarily a niri issue. Maybe try doing some cross-tests for example test it under Hyprland. Despite the window size issue, if issuing a niri fullscreen-window command (via bind if you have something like Mod+Shift+F { fullscreen-window; } in the config) works? And I suspect PROTON_ENABLE_WAYLAND=1 is working or not here because usually it would make some difference. Be sure the proton you're using is not the Steam default one (afaik steam upstream proton does not have winewayland yet).

[Sempyos]

@gmbhneo

[gmbhneo]

I've tried hyprland, KDE Plasma and COSMIC... all of them don't show this issue. Also tried DMS, noctalia and niri bare bone. Only niri does show the issue. I've also played with lots of proton versions and other parameters. The only thing "fixing" the issue is by using gamescope. However, I would want to prevent that for better latency.