Left off-screen window visible after scrolling to the right

[quantumsnow]

When there is a window off-screen to the left, I can see one pixel line of the edge of that window but it should be just outside the screen:

This only happens when I arrived at this position after scrolling to the right. When I get there scrolling left, the line is not visible:

Here is a video of the two different scrolling directions:

2026-02-08.18-01-42.trimmed.mp4

From the screenshot it appears that the gap to the left is 24 (physical) pixels after scrolling right but 23 after scrolling left. If I understand correctly, it should always be 10*2.25 = 22.5 = 23 after rounding (logical pixel gap times scaling factor).

This might be related to #640 and #3343 but since the dependence on scrolling direction seems new, I thought I'd report still.

Config

// I use the default config but include this file with alterations as well as DMS configs

input {
	touchpad {
		tap
		natural-scroll
		dwt
	}
	keyboard {
		xkb {
            options "compose:ralt"
		}
	}
	mouse {
		natural-scroll
	}
}

cursor {
    xcursor-theme "Bibata-Modern-Classic"
    hide-after-inactive-ms 30000
}

output "eDP-1" {
	scale 2.25
	position x=0 y=0
}

output "PNP(BNQ) BenQ BL2710 N1E06228SL0" {
    focus-at-startup
    position x=1707 y=-300
}

//Iiyama North America PL2497H
output "DP-1" {
    mode "1920x1080@100"
    position x=0 y=-1080
}

layout {
	gaps 10
	shadow { on; }
	focus-ring {
		width 0
	}
	//background-color "white"
}

/-layer-rule {
	match namespace="^quickshell$"
	place-within-backdrop true
}

/-layer-rule {
	match namespace="dms:blurwallpaper"
	place-within-backdrop true
}

spawn-at-startup "bash" "-c" "wl-paste --watch cliphist store &"

prefer-no-csd

window-rule {
    geometry-corner-radius 20
}

window-rule {
    match app-id="org.gnome.NautilusPreviewer"
    open-floating true
}

/-window-rule {
    match app-id="com.nextcloud.desktopclient.nextcloud" title="Nextcloud"
    open-floating true
}

window-rule {
    match app-id="librewolf"
    open-maximized true
}

window-rule {
    match app-id="protonvpn-app"
    open-floating true
}

window-rule {
	match app-id="org.gnome.Papers"
	open-maximized true
}

hotkey-overlay {
    skip-at-startup
}

binds {
    Mod+T hotkey-overlay-title="Open a Terminal: Ptyxis" { spawn "ptyxis" "--new-window"; }
    
    Mod+Shift+Down { focus-workspace-down; }
    Mod+Shift+Up { focus-workspace-up; }
    
    Mod+Ctrl+Shift+Down { move-window-to-workspace-down; }
    Mod+Ctrl+Shift+Up { move-window-to-workspace-up; }
    
    Mod+Alt+Down { move-workspace-down; }
    Mod+Alt+Up { move-workspace-up; }

    Mod+Shift+Ctrl+Left { move-window-to-monitor-left; }
    Mod+Shift+Ctrl+Right { move-window-to-monitor-right; }
    
    Mod+Alt+Left { move-workspace-to-monitor-left; }
    Mod+Alt+Right { move-workspace-to-monitor-right; }
    
    Mod+Ctrl+B { toggle-window-floating; }
    Mod+B { switch-focus-between-floating-and-tiling; }
    
    Mod+L hotkey-overlay-title="Lock Screen" { 
        spawn "dms" "ipc" "call" "lock" "lock"; 
    }
}

gestures {
    hot-corners {
        off
    }
}

environment {
    //dms
    XDG_CURRENT_DESKTOP "niri"
    QT_QPA_PLATFORM "wayland"
    ELECTRON_OZONE_PLATFORM_HINT "auto"
    QT_QPA_PLATFORMTHEME "gtk3"
    QT_QPA_PLATFORMTHEME_QT6 "gtk3"
}

System Information

• niri version: niri 25.11

• Distro: Bluefin 43

• GPU: Intel UHD Graphics 620

• CPU: Intel Core i7-8550U

[Sempyos]

Can you try with other apps, such as alacritty..?

[quantumsnow]

Yes, happens with every app I've tried. Screenshot of Alacritty:

[Sempyos]

Probably fractional scaling issue then, in assuming if you set your scale to 2 it would behave correctly

[YaLTeR]

I'm gonna guess that this is because with fractional scale we have to round the window size (protocol requirement), so it ends up 1 physical px shorter than the screen. Isn't really much we can do about this.

[quantumsnow]

Yes, can confirm that when setting scale to 2, the issue does not occur. Similarly, with scaling at 2.25 but setting the gap size to 8 (so physical gap size is exactly 18), the issue also does not occur.
It is curious though, that it never happens on the right of the screen in either scrolling direction.
Anyway, not a big issue so feel free to close.

[Sempyos]

Closing as uh fractional scale as YaLTeR said aboves

[Sempyos]

Also feel free to post your stuff in: #640