Mailspring/packages/client-app/internal_packages/onboarding/lib/page-top-bar.jsx

import React from 'react';
import {AccountStore} from 'nylas-exports';
import {RetinaImg} from 'nylas-component-kit';
import OnboardingActions from './onboarding-actions';

const PageTopBar = (props) => {
  const {pageDepth} = props;

  const closeClass = (pageDepth > 1) ? 'back' : 'close';
  const closeIcon = (pageDepth > 1) ? 'onboarding-back.png' : 'onboarding-close.png';
  const closeAction = () => {
    const webview = document.querySelector('webview');
    if (webview && webview.canGoBack()) {
      webview.goBack();
    } else if (pageDepth > 1) {
      OnboardingActions.moveToPreviousPage();
    } else {
      if (AccountStore.accounts().length === 0) {
        NylasEnv.quit();
      } else {
        NylasEnv.close();
      }
    }
  }

  let backButton = (
    <div className={closeClass} onClick={closeAction}>
      <RetinaImg name={closeIcon} mode={RetinaImg.Mode.ContentPreserve} />
    </div>
  )
  if (props.pageDepth > 1 && !props.allowMoveBack) {
    backButton = null;
  }

  return (
    <div
      className="dragRegion"
      style={{
        top: 0,
        left: 26,
        right: 0,
        height: 27,
        zIndex: 100,
        position: 'absolute',
        WebkitAppRegion: "drag",
      }}
    >
      {backButton}
    </div>
  )
}

PageTopBar.propTypes = {
  pageDepth: React.PropTypes.number,
  allowMoveBack: React.PropTypes.bool,
};

export default PageTopBar;