crate feature tokio fails to build

[anishsinha-io]

Building floem with crate feature tokio on (at least) the last three commits of main fail with the following error (tested with the example in the GitHub readme):

error[E0308]: mismatched types
   --> /Users/anishsinha/.cargo/git/checkouts/floem-69eea0a757d1e3ee/5ab32a2/src/ext_event.rs:232:52
    |
232 |             crate::ext_event::register_ext_trigger(trigger);
    |             -------------------------------------- ^^^^^^^ expected `ExtSendTrigger`, found `Trigger`
    |             |
    |             arguments to this function are incorrect
    |
note: function defined here
   --> /Users/anishsinha/.cargo/git/checkouts/floem-69eea0a757d1e3ee/5ab32a2/src/ext_event.rs:85:8
    |
85  | pub fn register_ext_trigger(trigger: ExtSendTrigger) {
    |        ^^^^^^^^^^^^^^^^^^^^ -----------------------

For more information about this error, try `rustc --explain E0308`.
error: could not compile `floem` (lib) due to 1 previous error

Steps to reproduce

Paste the following in your main.rs

use floem::prelude::*;

fn main() {
    floem::launch(counter_view);
}

fn counter_view() -> impl IntoView {
    let mut counter = RwSignal::new(0);

    h_stack((
        button("Increment").action(move || counter += 1),
        label(move || format!("Value: {counter}")),
        button("Decrement").action(move || counter -= 1),
    ))
    .style(|s| s.size_full().items_center().justify_center().gap(10))
}

Put the following in your Cargo.toml

floem = { git = "https://github.com/lapce/floem.git", features = ["tokio"] }

It's worth noting that this issue is NOT present in the latest release version (0.2.0), so if you use version 0.2.0 the build will succeed. I don't know when exactly this regressed, however, I tested with the last few commits on main.

Next steps

It didn't look like too difficult of a fix so I attempted to patch it. If you run the example with the following dependency:

floem = { git = "https://github.com/anishsinha-io/floem.git", features = [
  "tokio",
], branch = "fix-signal-from-tokio-channel" }

then the build will succeed. At least, it did for me on a m1 max macbook. I'll make a PR for you all to review soon.