Usually, you would use the method:

systemTrayIcon.addEventListener("click", function() {
window.nativeWindow.orderToFront();
});

But doing so will result in… actually nothing at all. The window doesn’t move.
Using the same code on a menu item of the SystemTrayIcon will work, but not on the click action of the Icon itself.

Workaround:

Set the window property alwaysInFront to true and then to false:

systemTrayIcon.addEventListener("click", function() {
 window.nativeWindow.alwaysInFront = true;
 window.nativeWindow.alwaysInFront = false;
 });

Not the way it should be, but it works…