Add hide/show ability for panels

src/panel-element.coffee

@@ -8,8 +8,18 @@ class PanelElement extends HTMLElement
 
   setModel: (@model) ->
     @appendChild(@model.getItemView())
+    @subscriptions.add @model.onDidChangeVisible(@visibleChanged.bind(this))
     @subscriptions.add @model.onDidDestroy(@destroyed.bind(this))
 
+  attachedCallback: ->
+    @visibleChanged(@model.isVisible())
+
+  visibleChanged: (visible) ->
+    if visible
+      @style.display = null
+    else
+      @style.display = 'none'
+
   destroyed: ->
     @subscriptions.dispose()
     @parentNode?.removeChild(this)

src/panel.coffee

@@ -3,16 +3,13 @@
 # Public:
 module.exports =
 class Panel
-  constructor: ({@viewRegistry, @item}) ->
+  constructor: ({@viewRegistry, @item, @visible}) ->
     @emitter = new Emitter
+    @visible ?= true
 
   destroy: ->
     @emitter.emit 'did-destroy', this
 
-  getView: -> @viewRegistry.getView(this)
-
-  getItemView: -> @viewRegistry.getView(@item)
-
   ###
   Section: Event Subscription
   ###
@@ -24,3 +21,26 @@ class Panel
   # Returns a {Disposable} on which `.dispose()` can be called to unsubscribe.
   onDidDestroy: (callback) ->
     @emitter.on 'did-destroy', callback
+
+  onDidChangeVisible: (callback) ->
+    @emitter.on 'did-change-visible', callback
+
+  ###
+  Section: Panel Details
+  ###
+
+  getView: -> @viewRegistry.getView(this)
+
+  getItemView: -> @viewRegistry.getView(@item)
+
+  isVisible: -> @visible
+
+  hide: ->
+    wasVisible = @visible
+    @visible = false
+    @emitter.emit 'did-change-visible', @visible if wasVisible
+
+  show: ->
+    wasVisible = @visible
+    @visible = true
+    @emitter.emit 'did-change-visible', @visible unless wasVisible