Add panel containers

src/panel-container-element.coffee

@@ -0,0 +1,28 @@
+{CompositeDisposable} = require 'event-kit'
+
+class PanelContainerElement extends HTMLElement
+  createdCallback: ->
+    @subscriptions = new CompositeDisposable
+
+  getModel: -> @model
+
+  setModel: (@model) ->
+    @subscriptions.add @model.onDidAddPanel(@panelAdded.bind(this))
+    @subscriptions.add @model.onDidRemovePanel(@panelRemoved.bind(this))
+    @subscriptions.add @model.onDidDestroy(@destroyed.bind(this))
+
+  panelAdded: ({panel, index}) ->
+    if index >= @childNodes.length
+      @appendChild(panel.getView())
+    else
+      referenceItem = @childNodes[index + 1]
+      @insertBefore(panel.getView(), referenceItem)
+
+  panelRemoved: ({panel, index}) ->
+    @removeChild(@childNodes[index])
+
+  destroyed: ->
+    @subscriptions.dispose()
+    @parentNode?.removeChild(this)
+
+module.exports = PanelContainerElement = document.registerElement 'atom-panel-container', prototype: PanelContainerElement.prototype

src/panel-container.coffee

@@ -0,0 +1,48 @@
+{Emitter, CompositeDisposable} = require 'event-kit'
+
+# Public:
+module.exports =
+class PanelContainer
+  constructor: ({@viewRegistry}) ->
+    @emitter = new Emitter
+    @subscriptions = new CompositeDisposable
+    @panels = []
+
+  destroy: ->
+    pane.destroy() for pane in @getPanels()
+    @subscriptions.dispose()
+    @emitter.emit 'did-destroy', this
+    @emitter.dispose()
+
+  ###
+  Section: Event Subscription
+  ###
+
+  onDidAddPanel: (callback) ->
+    @emitter.on 'did-add-panel', callback
+
+  onDidRemovePanel: (callback) ->
+    @emitter.on 'did-remove-panel', callback
+
+  onDidDestroy: (callback) ->
+    @emitter.on 'did-destroy', callback
+
+  ###
+  Section: Panels
+  ###
+
+  getView: -> @viewRegistry.getView(this)
+
+  getPanels: -> @panels
+
+  addPanel: (panel) ->
+    @subscriptions.add panel.onDidDestroy(@panelDestoryed.bind(this))
+    index = @panels.length
+    @panels.push(panel)
+    @emitter.emit 'did-add-panel', {panel, index}
+
+  panelDestoryed: (panel) ->
+    index = @panels.indexOf(panel)
+    if index > -1
+      @panels.splice(index, 1)
+      @emitter.emit 'did-remove-panel', {panel, index}