Handle fullscreen state without accessing remote.window

First step of getting remote out of the codebase.

lib/fullscreen.js

@@ -2,12 +2,12 @@ const electron = require('electron')
 const { Value } = require('mutant')
 
 module.exports = function () {
-  const win = electron.remote.getCurrentWindow()
-  const isFullScreen = Value(win.isFullScreen())
-  win.on('enter-full-screen', () => {
+  const isFullScreen = Value(false)
+  // receive the OS window state from the main process
+  electron.ipcRenderer.on('enter-full-screen', () => {
     isFullScreen.set(true)
   })
-  win.on('leave-full-screen', () => {
+  electron.ipcRenderer.on('leave-full-screen', () => {
     isFullScreen.set(false)
   })
   return isFullScreen

lib/window.js

@@ -11,6 +11,14 @@ module.exports = function Window (config, path, opts) {
     }
   }, opts))
 
+  // have to forward the OS window state to the renderer because it cannot
+  // access directly
+  window.on('enter-full-screen', (event, alwaysOnTop) => {
+    window.webContents.send("enter-full-screen");
+  })
+  window.on('leave-full-screen', (event, alwaysOnTop) => {
+    window.webContents.send("leave-full-screen");
+  })
   electron.ipcMain.on('ready-to-show', handleReadyToShow)
 
   window.webContents.on('dom-ready', function () {