assertion 'width >= -1' failed on NixOS/Sway

[Zachiah]

When trying to run one of the examples from the book, the window is created, but no widgets render:

use druid::widget::Label;
use druid::{AppLauncher, Widget, WindowDesc};

fn build_ui() -> impl Widget<()> {
    Label::new("Hello world")
}

fn main() {
    let main_window = WindowDesc::new(build_ui())
        .window_size((600.0, 400.0))
        .title("My first Druid App");
    let initial_data = ();

    AppLauncher::with_window(main_window)
        .launch(initial_data)
        .expect("Failed to launch application");
}

In the console I get this error:

(rust-plugin-try:190043): Gtk-CRITICAL **: 16:10:25.770: gtk_window_set_default_size: assertion 'width >= -1' failed

I apologize if this isn't the right place to put this issue, but I haven't had any issues running apps so far so It seems to be specific to this project? I'm willing to provide any version numbers/environment variables asked of me, but here are some basics:

Rust: 1.75.0
Druid: 0.8.3
Sway: 1.8.1
Nix: 2.18.1
Neofetch (logo removed):

zachiahsawyer@nixos
-------------------
OS: NixOS 23.11.2413.32f63574c85f (Tapir) x86_64
Host: LENOVO LNVNB161216
Kernel: 6.6.8
Uptime: 20 hours, 25 mins
Packages: 763 (nix-system), 1008 (nix-user)
Shell: zsh 5.9
Resolution: 3072x1920
WM: sway
Theme: Catppuccin-Macchiato-Compact-Pink-Dark [GTK2/3]
Terminal: alacritty
CPU: AMD Ryzen 7 6800HS Creator Edition (16) @ 4.785GHz
GPU: AMD ATI Radeon 680M
GPU: NVIDIA GeForce RTX 3050 Mobile
Memory: 11912MiB / 13669MiB

Also, I don't know how relevant it is, but I'm using a shell.nix file to setup the environment

which looks like this:

{ pkgs ? import <nixpkgs> {} }:

pkgs.mkShell {
    buildInputs = [
        pkgs.alsaLib
        pkgs.pkg-config
        pkgs.pango
        pkgs.cairo
        pkgs.gdk-pixbuf
        pkgs.gtk3
    ];
    shellHook = ''
        export PKG_CONFIG_PATH=${pkgs.alsaLib}/lib/pkgconfig:${pkgs.pango}/lib/pkgconfig:${pkgs.cairo}/lib/pkgconfig:${pkgs.gdk-pixbuf}/lib/pkgconfig:${pkgs.gtk3}/lib/pkgconfig:$PKG_CONFIG_PATH
    '';
}

[jaredoconnell]

This works on Windows. The error is Gtk specific, and you're on Linux so it's using GTK by default.

It's complaining about the default size. Maybe try changing the size settings with .with_min_size((200., 200.))
And if that fails, see if it works with the flag gtk disabled, and druid-shell/wayland or druid-shell/x11 enabled, to bypass gtk.

[colemickens]

I'm confused, do we understand why:

1. This affects NixOS users more / exclusively? Do we build with different features that cause druid to select different backends than otherwise? Or is there something weird about our GTK that causes this assert to be more problematic than users on other distros?

2. Do we know why some users (in psst) were reporting that it worked under GNOME but not KDE? That seems even more confusing?

3. And finally, why doesn't druid work around this by setting a min_size automatically for GTK?

[RensOliemans]

Adding .with_min_size((200., 200.)) (or replacing the original .window_size() with it) doesn't fix it. Adding x11 to the features does work, and so does running the program with GDK_BACKEND=x11.

I'm also running NixOS. It seems like it's unique to NixOS which is interesting.