Tile Split View: TweetDeck | Discord https://github.com/kasper/phoenix

.phoenix.js

/**
 * SplitView
 */
const splitView = ({ leftAppName, rightAppName, mainAppName }) => {
    const leftApp = App.get(leftAppName);
    const leftAppWindow = leftApp.mainWindow();
    const rightApp = App.get(rightAppName);
    const rightAppWindow = rightApp.mainWindow();
    const frame = Screen.main().visibleFrame();
    const { width, height } = frame;

    const windowRatio = {
        left: 0.73,
        right: 0.27
    };
    // Resize
    leftAppWindow.setFrame({ x: 0, y: 0, width: width * windowRatio.left, height });
    rightAppWindow.setFrame({ x: width * windowRatio.left, y: 0, width: width * windowRatio.right, height });
    // raise up to front
    if (leftAppName === mainAppName) {
        rightAppWindow.raise();
        leftAppWindow.raise();
    } else {
        leftAppWindow.raise();
        rightAppWindow.raise();
    }
}

const appNames = {
    left: "TweetDeck",
    right: "Discord"
}
// on active
Event.on('appDidActivate', app => {
    const appName = app.name();
    if (appName === appNames.left || appName === appNames.right) {
        splitView({
            leftAppName: appNames.left,
            rightAppName: appNames.right,
            mainAppName: appName
        });
    }
});