window:Popup(props) floats a modal card over a dimmed backdrop. Give it options for a choice dialog, or boxes for a changelog. It returns a handle with Close().

A choice dialog
A changelog
Properties
The heading.
A smaller line beneath the title.
An icon beside the title.
A body paragraph. Wraps, and scrolls inside the card when long.
A list of cards, shown instead of a paragraph. Each
box takes title, and optional description and icon.Footer buttons. Each
option takes text, an optional style ("neutral", "primary", or "danger"), and an optional callback that runs before the popup closes.Let the player click the backdrop or press Escape to close.