add electron api

Author: wangb

source/_drafts/electron-api.md

@@ -0,0 +1,28 @@
+---
+title: electron-api
+tags:
+---
+
+## Process
+1. Main Process and Render Proccess (`BrowserWindow` module)
+2. Main process is responsible for creating and managing `BrowserWindow` and application events.
+2. In The Render Process we can get `BrowserWindow` module and other electron module by `electron.remote`
+3. `ipcMain, ipcRender` module allows you to send and receive synchronous(`sendSync`) and asynchronous(`send`) messages between the main and render processes.
+
+## Window
+3. There is a option(`{show: false}`) for `BrowserWindow` can hide the window, which can be used for background task.
+4. we use `BrowserWindow.loadURL` to load html for our works. 
+4. We can listen various events on window like `focus, blur, close` etc. There are also `unresponsive, responsive` event on `BrowserWindow` and `crashed` event on `BrowserWindow.webContents`
+5. window can be frameless, without toolbars, title bars, status bars, borders (`{frame: false}`).
+6. WebContents: we can send event to window
+
+## Menu
+- Two kinds of menus: application menu, context menu
+- Two modules: `electron.Menu, electron.MenuItem` (alse in remote)
+
+## Native User Interface
+- `shell`: open external links and the file manager
+- `dialog`: system dialogs
+- `Tray`
+
+## System