Trying to get Screenshot to work.

[John-Nagle]

Trying to get Egui's Screenshot feature to work.
Test program:

git clone https://github.com/John-Nagle/ui-mock.git 
cd ui-mock
git checkout screenshot
cargo build --examples
cd target/release/examples
./ui-mock

Select one of the dummy metaverse buttons, go through the dummy login (username and password do nothing), and get the 3D cube on screen. Use the Developer->Screenshot menu.

This executes

                        if ui
                            .button(t!("menu.developer.screenshot", state.get_lang()))
                            .clicked()
                        {
                            println!("Screenshot");
                            ui
                                .ctx()
                                .send_viewport_cmd(ViewportCommand::Screenshot(UserData::default()));
                        }

And "Screenshot" is printed.

On the event processing side, the code to look for a Screenshot event, in "screenshot.rs", is

pub fn check_for_screenshot(state: &CommonState) {
    let ctx = state.context.clone();
    let image = ctx.input(|i| {
        i.events
            .iter()
            .filter_map(|e| {
                println!("EGUI Event: {:?}", e); // ***TEMP***
                if let egui::Event::Screenshot { image, .. } = e {
                    Some(image.clone())
                } else {
                    None
                }
            })
            .last()
    });

    if let Some(image) = image {
        println!("Got screenshot.");
    }
}

This prints lots of other events, but no Screenshot event.

This code is modeled after the example at https://github.com/emilk/egui/blob/master/examples/screenshot/src/main.rs
What am I doing wrong?