Looking for an example how to open multiple files at once

I'm looking for a minimal example showing how to open multiple files.

Here is what I tried unsuccessfully.

commands::SHOW_OPEN_PANEL.with(
 FileDialogOptions::new()
 .multi_selection()
 .button_text("Open"),
)

but it's not triggering commands::OPEN_FILES. It keeps triggering commands::OPEN_FILE even if I select multiple files.