0.0.38: light gray 7px border on left/right/bottom on i3/X11 without compositor

[mo]

Human explanation: When I upgraded to t3-code 0.0.38 I got a weird light gray border left/right/bottom of the window. I use ubuntu 24.04 and i3 window manager. The bug was caused by the electron version bump and it looks like this:

Version

T3-Code 0.0.38 AppImage (T3-Code-0.0.38-x86_64.AppImage), Electron 43.4.1 (bumped in #8626)

Previous version (0.0.37) had no border.

Environment

• OS: Ubuntu 24.04.4 LTS (Noble)
• WM: i3 4.23 on X11 (XDG_SESSION_TYPE=x11, $DISPLAY=:0, no WAYLAND_DISPLAY)
• No compositor: no picom/compton, xprop -root _NET_WM_CM_S0 -> not found
• Launch: ~/opt/T3-Code-*-x86_64.AppImage --force-device-scale-factor=1.75

Describe the bug

After upgrading to 0.0.38, a light gray border appears on left/right/bottom sides of the main window (top is clean). Looks like 6-7px solid #EBEBEB with 1px darker #C8C8C8 outer edge.

Screenshot pixel sampling (3840x2160 fullscreen):

• left edge at mid-height: x=0: (200,200,200), x=1-6: (235,235,235), x=7+: app bg (32,46,60) = ~7px
• right edge: ~5-7px (235,235,235)
• bottom edge just above i3bar: y=2118: (209,209,209), y=2113-2117: (235,235,235), y=2112: app bg = ~6px
• top: no border, app bg from y=0

X11 properties:

xwininfo: Border width: 0, 3840x2119+0+0
xprop _GTK_FRAME_EXTENTS(CARDINAL) = 7, 7, 0, 7
_NET_WM_WINDOW_TYPE = NORMAL, WM_CLASS = "t3code"
_MOTIF_WM_HINTS = 0x2, 0x0, 0x0, 0x0, 0x0

So this is not an i3 border (width 0), it is in-client CSD shadow area rendered opaque because there is no compositor to make it transparent.

Expected

No visible border on non-compositing X11 WMs like i3, as in 0.0.37. Either:

• detect lack of compositing / client-shadow support and render with no insets (like Chrome falls back to SSD), or
• create frameless window with hasShadow: false, or expose an option for it.

Upstream

This matches electron/electron#52024
"Linux: frameless windows have a border on non-compositing X11 WMs, e.g. i3"

A frameless window should not have any border on i3, which is an X11 window manager which does not have a compositor out of the box and cannot support shadows. The window has a border around the sides and bottoms where the shadow would appear.

That issue notes Electron 41+ added CSD to frameless windows, and LinuxFrameLayout::Create / X11Window::CanSetDecorationInsets path falls back to a resize border when the WM doesn't advertise _GTK_FRAME_EXTENTS (i3 case).

Workaround

Running picom -b makes the 7px area transparent shadow again. Downgrading to 0.0.37 also removes it. Filing here because T3-Code owns the BrowserWindow options and Electron bump.

[juliusmarminge]

Triage

Confirmed visual regression in 0.0.38, desktop-only. Root cause is Electron 43 CSD, not an i3 border.

What we checked

• 0.0.37 shipped Electron 41.5.0. 0.0.38 shipped Electron 43.4.1 via chore(deps): bump Electron to 43.4.1 #8626. DesktopWindow title-bar options did not change between those tags.
• Linux/Windows main windows use titleBarStyle: "hidden" + titleBarOverlay (apps/desktop/src/window/DesktopWindow.ts, from window controls overlay (windows&linux) #1969). That is Chromium CSD. There is no hasShadow: false and no compositor / _GTK_FRAME_EXTENTS check. The WSL splash uses frame: false and would hit the same path.
• Your _GTK_FRAME_EXTENTS = 7, 7, 0, 7 and the left/right/bottom-only band match Electron drawing a resize/shadow inset with no compositor to make it transparent. xwininfo border width 0 rules out i3 chrome.

This is the same bug as electron/electron#52024 (last good 42.4.1, broken in 43). i3 does not advertise _GTK_FRAME_EXTENTS; X11Window::CanSetDecorationInsets then falls back to an opaque resize border. Upstream notes that hasShadow: false still leaves a gap; Chrome falls back to server-side decorations instead.

#5398 (Linux native-frame setting) would avoid this via frame: true, but it was closed as extra window-mode cost for a preference, not a regression. We should not reopen that as the first fix.

Workaround

picom -b (or another compositor), or stay on 0.0.37, until we ship a fallback or Electron fixes #52024.

Next step

Accept. Preferred T3-side fix: smallest automatic fallback on Linux X11 without client-shadow support — skip the hidden overlay and use frame: true (SSD), like Chrome. Do not add a settings toggle unless that fallback is not enough. Also keep watching Electron #52024; the next Electron bump may inherit a fix.

Web / mobile / providers: not involved.