Multi window freeze

[probablykasper]

Describe the bug

Creating a new window like this makes the app unresponsive on macOS:

#[command]
pub fn new_window(app_handle: AppHandle) -> Result<(), String> {
  println!("new w");
  app_handle
    .create_window("main2".to_string(), WindowUrl::default(), |win, webview| {
      let win = win
        .title("Main 2")
        .resizable(true)
        .transparent(false)
        .decorations(true)
        .always_on_top(false)
        .inner_size(800.0, 600.0)
        .min_inner_size(300.0, 150.0)
        .fullscreen(false);
      println!("- struct created");
      return (win, webview);
    })
    .expect("Error creating window");
  println!("- done");
  Ok(())
}

To Reproduce

Repo: https://github.com/probablykasper/tauri-multiwindow-freeze-bug

Platform and Versions (required):

Operating System - Mac OS, version 10.15.7 X64

Node.js environment
  Node.js - 14.16.0
  @tauri-apps/cli - 1.0.0-beta.6
  @tauri-apps/api - 1.0.0-beta.5

Global packages
  npm - 6.14.11
  yarn - 1.22.10

Rust environment
  rustc - 1.52.1
  cargo - 1.52.0

App directory structure
/node_modules
/src-tauri
/build
/.git
/src

App
  tauri.rs - 1.0.0-beta.5
  build-type - bundle
  CSP - default-src blob: data: filesystem: ws: wss: http: https: tauri: 'unsafe-eval' 'unsafe-inline' 'self' img-src: 'self'
  distDir - ../build
  devPath - http://localhost:4000
  framework - Svelte

[amrbashir]

I can reproduce this issue on windows with your repo but can't reproduce it with our multiwindow example.

[probablykasper]

@amrbashir I think the multiwindow example only creates windows from tauri.conf.json and/or tauri::Builder

[amrbashir]

No, it creates from commands too.
Edit: it creates it from the js side.

[probablykasper]

@amrbashir Ah, so then it calls this internal command:

tauri/core/tauri/src/endpoints/window.rs

Lines 115 to 128 in fd8fab5

	Self::CreateWebview { options } => {
	let mut window = window;
	let label = options.label.clone();
	let url = options.url.clone();
	window
	.create_window(label.clone(), url, |_, webview_attributes| {
	(
	<<R::Dispatcher as Dispatch>::WindowBuilder>::with_config(options),
	webview_attributes,
	)
	})?
	.emit_others("tauri://window-created", Some(WindowCreatedEvent { label }))?;
	}

[amrbashir]

@amrbashir Ah, so then it calls this internal command:

yeah but we still need to figure out why it doesn't work from commands, doesn't matter which attributes you set too

#[command]
pub fn new_window(app_handle: AppHandle) -> Result<(), String> {
  println!("new w");
  app_handle
    .create_window("main2".to_string(), WindowUrl::default(), |win, webview| (win, webview))
    .expect("Error creating window");
  println!("- done");
  Ok(())
}

[lucasfernog]

It doesn't work because the command is not async, which means it is ran on the main thread and it's preventing the event loop from receiving the message.

Changing the #[command] pub fn to #[command] pub async fn will make it work.