MainMenu.tsx

import * as Bifrost from 'bifrost';

export default class MainMenu extends Bifrost.GUI.Control {

    private handleButtonClick(event: Event): void {
        console.log('Button Click:', event);
    }

    public render(): Bifrost.GUI.Control.Tree {
        return [
            <HTMLButtonElement onclick={ (e: Event) => this.handleButtonClick(e) }>
                Click Here
            </HTMLButtonElement>
        ];
    }

    public theme(): Bifrost.GUI.Control.Style {
        return `
            .${ HTMLButtonElement.name } {
                background: blue;
                color: white;
            }
        `;
    }
}