How to create a topbottom window that is never covered by other topbottom windows?

Question

How to create a topbottom window that is never covered by other topbottom windows?

I want to have the n (currently only two, but I need more) largest windows, but not allowing them to be closed by the other most remote windows that were created earlier.

So, suppose we have 3 windows like this, created in the following order:

A
IN
FROM

Acannot cover Bor C. Bwill cover only Abut not C. Cwill cover Aand Bwill not be covered by any of the previously created windows ( Aor B).

To create windows, I used ElectronJS (the former atomic shell) and did the following:

var App = require('app')
  , BrowserWindow = require('browser-window')
  ;

var mainWindow = null;

...

App.on('ready', function() {
    mainWindow = new BrowserWindow({
        width: 100
      , height: 50
      , resizable: false
      , frame: false
      , type: "desktop"
    });
    mainWindow.loadUrl('file://' + __dirname + '/../index.html');
    ...
});