in src/Popout.tsx [228:242]
private renderChildWindow() {
validateUrl(this.props.url!);
if (!this.props.hidden) {
if (!isChildWindowOpened(this.child)) {
this.openChildWindow();
}
if (!this.props.url && this.container) {
ReactDOM.render(this.props.children, this.container);
}
} else {
this.closeChildWindowIfOpened();
}
}