diff --git a/app/commons/File/subscribeToFileChange.js b/app/commons/File/subscribeToFileChange.js
index 863f0274..8526d33e 100644
--- a/app/commons/File/subscribeToFileChange.js
+++ b/app/commons/File/subscribeToFileChange.js
@@ -43,6 +43,12 @@ function handleGitFiles (node) {
   return false
 }
 
+// fixme: maybe we should make this a standard method of File model
+function fileIsOpened (filePath) {
+  const openedFilePaths = mobxStore.EditorState.entities.values().map(editor => editor.filePath)
+  return openedFilePaths.includes(filePath)
+}
+
 export default function subscribeToFileChange () {
   autorun(() => {
     if (!config.fsSocketConnected) return
@@ -51,27 +57,22 @@ export default function subscribeToFileChange () {
     client.subscribe(`/topic/ws/${config.spaceKey}/change`, (frame) => {
       const data = JSON.parse(frame.body)
       const node = data.fileInfo
+
       switch (data.changeType) {
         case 'create':
-          if (handleGitFiles(node)) {
-            break
-          }
-          FileActions.loadNodeData([node])
-          break
         case 'modify':
           if (handleGitFiles(node)) {
             break
           }
-          FileActions.loadNodeData([node])
-          const tabsToUpdate = mobxStore.EditorTabState.tabs.values().filter(tab => tab.path === node.path)
-          if (tabsToUpdate.length) {
+          if (!node.isDir && fileIsOpened(node.path)) {
             api.readFile(node.path).then(({ content }) => {
-              TabActions.updateTabByPath({
-                path: node.path,
-                content,
-              })
+              node.content = content
+              FileActions.loadNodeData([node])
             })
+          } else {
+            FileActions.loadNodeData([node])
           }
+
           break
         case 'delete':
           FileActions.removeNode(node)
diff --git a/app/commons/Tree/state.js b/app/commons/Tree/state.js
index 0737f538..05223f57 100644
--- a/app/commons/Tree/state.js
+++ b/app/commons/Tree/state.js
@@ -1,5 +1,6 @@
 import _ from 'lodash'
 import { observable, computed, action, autorun } from 'mobx'
+import { protectedObservable } from 'utils/decorators'
 
 function TreeNodeScope () {
   const SHADOW_ROOT_NODE = 'SHADOW_ROOT_NODE'
@@ -28,17 +29,13 @@ function TreeNodeScope () {
       state.entities.set(this.id, this)
     }
 
-  @observable _isDir = false
-  @observable _name = ''
-  @computed get name () { return this._name }
-    set name (v) { return this._name = v }
-  @computed get isDir () { return this._isDir }
-    set isDir (v) { return this._isDir = v }
+  @protectedObservable _name = ''
+  @protectedObservable _isDir = false
+  @protectedObservable _parentId = undefined
 
   @observable isFolded = true
   @observable isFocused = false
   @observable isHighlighted = false
-  @observable parentId = undefined
   @observable index = 0
 
   @computed get isShadowRoot () {
diff --git a/app/components/Editor/components/CodeEditor/BaseCodeEditor.jsx b/app/components/Editor/components/CodeEditor/BaseCodeEditor.jsx
index 1b9e2500..53c2824a 100644
--- a/app/components/Editor/components/CodeEditor/BaseCodeEditor.jsx
+++ b/app/components/Editor/components/CodeEditor/BaseCodeEditor.jsx
@@ -30,6 +30,10 @@ class BaseCodeEditor extends Component {
       <div ref={r => this.dom = r} style={{ width: '100%', height: '100%' }} />
     )
   }
+
+  componentWillUnmount () {
+    this.editor.destroy()
+  }
 }
 
 BaseCodeEditor.propTypes = {
diff --git a/app/components/FileTree/actions.js b/app/components/FileTree/actions.js
index 9c824507..f5776c2c 100644
--- a/app/components/FileTree/actions.js
+++ b/app/components/FileTree/actions.js
@@ -67,9 +67,9 @@ export const toggleNodeFold = registerAction('filetree:toggle_node_fold',
   }
 )
 
-export const removeNode = registerAction('filetree:remove_node',
-  node => state.entities.delete(node.id)
-)
+export const removeNode = registerAction('filetree:remove_node', (node) => {
+  state.entities.delete(node.id || node.path)
+})
 
 export const openContextMenu = contextMenuStore.openContextMenuFactory(FileTreeContextMenuItems)
 export const closeContextMenu = contextMenuStore.closeContextMenu
diff --git a/app/components/FileTree/state.js b/app/components/FileTree/state.js
index 7329432c..738ae651 100644
--- a/app/components/FileTree/state.js
+++ b/app/components/FileTree/state.js
@@ -42,29 +42,29 @@ class FileTreeNode extends TreeNode {
     if (this.path === ROOT_PATH) this.isFolded = false
   }
 
-  @observable path = null
-
-  // override default name / isDir behavior
+  /* override base class */
   @computed get name () {
-    return this.file.name
+    return this.file ? this.file.name : ''
   }
 
   @computed get isDir () {
-    return this.file.isDir
-  }
-
-  @computed get file () {
-    return FileState.entities.get(this.path)
+    return this.file ? this.file.isDir : false
   }
 
-  @computed get parent () {
+  @computed get parentId () {
     // prioritize corresponding file's tree node
-    if (this.file) {
-      const parentFile = this.file && this.file.parent
-      if (parentFile === null) return state.shadowRoot
-      return state.entities.get(parentFile.path)
+    if (this.file && this.file.parent) {
+      return this.file.parent.path
     }
-    return null
+    return this._parentId
+  }
+  /* end override */
+
+  /* extend base class */
+  @observable path = null
+
+  @computed get file () {
+    return FileState.entities.get(this.path)
   }
 
   @computed get children () {
@@ -84,6 +84,7 @@ class FileTreeNode extends TreeNode {
   @computed get size () {
     if (this.file) return this.file.size
   }
+  /* end extend */
 }
 
 export default state
diff --git a/app/config.js b/app/config.js
index d84e2b38..8ea52817 100644
--- a/app/config.js
+++ b/app/config.js
@@ -14,6 +14,7 @@ const config = observable({
   fsSocketConnected: false,
   ttySocketConnected: false,
   fileExcludePatterns: ['/.git', '/.coding-ide'],
+  preventAccidentalClose: false,
 })
 
 window.config = config
diff --git a/app/initialize/state.js b/app/initialize/state.js
index eb309525..82d2e730 100644
--- a/app/initialize/state.js
+++ b/app/initialize/state.js
@@ -63,6 +63,18 @@ const stepCache = observable.map({
     func: () =>
       api.connectWebsocketClient()
   },
+  preventAccidentalClose: {
+    desc: 'Prevent accidental close',
+    func: () => {
+      window.onbeforeunload = function () {
+        if (config.preventAccidentalClose) {
+          return 'Do you really want to leave this site? Changes you made may not be saved.'
+        }
+        return void 0
+      }
+      return true
+    }
+  }
 })
 
 stepCache.insert = function (key, value, referKey, before = false) {
diff --git a/app/settings.js b/app/settings.js
index 82a5ec2b..1d1d2663 100644
--- a/app/settings.js
+++ b/app/settings.js
@@ -1,7 +1,8 @@
 import isObject from 'lodash/isObject'
+import { observable, reaction, extendObservable, computed, action } from 'mobx'
+import config from 'config'
 import emitter, { THEME_CHANGED } from 'utils/emitter'
 import is from 'utils/is'
-import { observable, reaction, extendObservable, computed, action, autorunAsync } from 'mobx'
 import dynamicStyle from 'utils/dynamicStyle'
 
 let EditorState
@@ -14,7 +15,7 @@ export const UIThemeOptions = [
 ]
 export const SyntaxThemeOptions = ['default', 'neo', 'eclipse', 'monokai', 'material']
 
-const changeTheme = (nextThemeId) => {
+const changeUITheme = (nextThemeId) => {
   if (!window.themes) window.themes = {}
   if (UIThemeOptions.map(option => option.value).includes(nextThemeId)) {
     import(`!!style-loader/useable!css-loader!stylus-loader!./styles/${nextThemeId}/index.styl`)
@@ -26,9 +27,10 @@ const changeTheme = (nextThemeId) => {
     })
   }
 
-  if (nextThemeId === 'dark' && EditorState.options.theme === 'default') {
+  const editorTheme = EditorState.options.theme
+  if (nextThemeId === 'dark' && (editorTheme === 'default' || editorTheme === 'neo' || editorTheme === 'eclipse')) {
     settings.theme.syntax_theme.value = 'material'
-  } else if (nextThemeId === 'base-theme' && (EditorState.options.theme === 'monokai' || EditorState.options.theme === 'material')) {
+  } else if (nextThemeId === 'base-theme' && (editorTheme === 'monokai' || editorTheme === 'material')) {
     settings.theme.syntax_theme.value = 'default'
   }
   emitter.emit(THEME_CHANGED, nextThemeId)
@@ -144,22 +146,21 @@ const settings = observable({
     ui_theme: {
       name: 'settings.theme.uiTheme',
       value: 'base-theme',
-      options: UIThemeOptions
+      options: UIThemeOptions,
+      reaction: changeUITheme,
     },
     syntax_theme: {
       name: 'settings.theme.syntaxTheme',
       value: 'default',
       options: SyntaxThemeOptions,
-      reaction (value) {
-        changeSyntaxTheme(value)
-      }
+      reaction: changeSyntaxTheme,
     }
   }),
 
   extensions: new DomainSetting({}),
 
   general: new DomainSetting({
-    _keys: ['language', 'hide_files'],
+    _keys: ['language', 'exclude_files'],
     requireConfirm: true,
     language: {
       name: 'settings.general.language',
@@ -169,9 +170,12 @@ const settings = observable({
       { name: 'settings.general.languageOption.chinese', value: 'Chinese' },
       ]
     },
-    hide_files: {
+    exclude_files: {
       name: 'settings.general.hideFiles',
-      value: '/.git,/.coding-ide'
+      value: config.fileExcludePatterns.join(','),
+      reaction (value) {
+        config.fileExcludePatterns = value.split(',')
+      }
     }
   }),
 
@@ -275,7 +279,3 @@ const settings = observable({
 })
 
 export default settings
-
-autorunAsync('changeTheme', () => {
-  changeTheme(settings.theme.ui_theme.value)
-})
diff --git a/app/utils/decorators/index.js b/app/utils/decorators/index.js
index d2aef227..d2984e5b 100644
--- a/app/utils/decorators/index.js
+++ b/app/utils/decorators/index.js
@@ -1,4 +1,5 @@
 import mapEntityFactory from './mapEntity'
 import defaultProps from './defaultProps'
+import protectedObservable from './protectedObservable'
 
-export { mapEntityFactory, defaultProps }
+export { mapEntityFactory, defaultProps, protectedObservable }
diff --git a/app/utils/decorators/protectedObservable.js b/app/utils/decorators/protectedObservable.js
new file mode 100644
index 00000000..56d7fbd7
--- /dev/null
+++ b/app/utils/decorators/protectedObservable.js
@@ -0,0 +1,40 @@
+import { observable, computed } from 'mobx'
+
+/*
+ * This decorator enforce a pattern that's widely used in this project,
+ *
+ *  @protectedObservable _foo = 'bar'
+ *
+ *  is a short hand for:
+ *
+ *  @observable _foo = 'bar'
+ *  @computed
+ *  get foo () { return this._foo }
+ *  set foo (value) { return this._foo = value }
+ *
+ *  you can specify publicKey explicitly by calling:
+ *  @protectedObservable('publicFoo') _foo = 'bar'
+ */
+function _protectedObservableDecorator (target, privateKey, descriptor, publicKey) {
+  if (!publicKey) publicKey = privateKey.replace(/^_/, '')
+
+  const computedDescriptor = computed(target, publicKey, {
+    get () { return this[privateKey] },
+    set (v) { return this[privateKey] = v },
+  })
+
+  Object.defineProperty(target, publicKey, computedDescriptor)
+
+  return observable(target, privateKey, descriptor)
+}
+
+function protectedObservable (optionalPublicKey) {
+  if (typeof optionalPublicKey === 'string') {
+    return function protectedObservableDecorator (target, key, descriptor) {
+      return _protectedObservableDecorator(target, key, descriptor, optionalPublicKey)
+    }
+  } else {
+    return _protectedObservableDecorator.apply(null, arguments)
+  }
+}
+export default protectedObservable