Fix issues with selections when switching between edit sessions

SelectionViews now update their appearance immediately when constructed. We can't assume they're empty. CursorView doesn't do a blanket `off()` call to its model when it's removed anymore, which was screwing up selection updates when switching back. Only attach selections / cursors when the editor is attached, and extract everything we do into a `renderWhenAttached` method.

src/app/cursor-view.coffee

@@ -13,13 +13,12 @@ class CursorView extends View
   hidden: false
 
   initialize: (@cursor, @editor) ->
-    @cursor.on 'change-screen-position', (position, options) =>
+    @cursor.on 'change-screen-position.cursor-view', (position, { bufferChange }) =>
       @updateAppearance()
-      unless options.bufferChange
-        @removeIdleClassTemporarily()
-      @trigger 'cursor-move', bufferChange: options.bufferChange
+      @removeIdleClassTemporarily() unless bufferChange
+      @trigger 'cursor-move', bufferChange: bufferChange
 
-    @cursor.on 'destroy', => @remove()
+    @cursor.on 'destroy.cursor-view', => @remove()
 
   afterAttach: (onDom) ->
     return unless onDom
@@ -28,7 +27,7 @@ class CursorView extends View
 
   remove: ->
     @editor.removeCursorView(this)
-    @cursor.off()
+    @cursor.off('.cursor-view')
     super
 
   updateAppearance: ->

src/app/editor.coffee

@@ -224,11 +224,11 @@ class Editor extends View
     @calculateDimensions()
     @hiddenInput.width(@charWidth)
     @setSoftWrapColumn() if @softWrap
-    @prepareForScrolling()
-    @setScrollPositionFromActiveEditSession() # this also renders the visible lines
-    @activeEditSession.on 'screen-lines-change', (e) => @handleRendererChange(e)
     $(window).on "resize.editor#{@id}", => @updateRenderedLines()
     @focus() if @isFocused
+
+    @renderWhenAttached()
+
     @trigger 'editor-open', [this]
 
   addCursorView: (cursor) ->
@@ -382,7 +382,6 @@ class Editor extends View
 
     if @activeEditSession
       @saveActiveEditSession()
-      @removeAllCursorViews()
       @activeEditSession.off()
 
     @activeEditSession = @editSessions[index]
@@ -394,24 +393,22 @@ class Editor extends View
     @trigger 'editor-path-change'
 
     @renderer = @activeEditSession.renderer
+    @renderWhenAttached()
 
-    if @attached
-      @prepareForScrolling()
-      @setScrollPositionFromActiveEditSession()
-      @renderLines()
-      @activeEditSession.on 'screen-lines-change', (e) => @handleRendererChange(e)
+  renderWhenAttached: ->
+    return unless @attached
 
-    for cursor in @activeEditSession.getCursors()
-      @addCursorView(cursor)
+    @removeAllCursorAndSelectionViews()
+    @addCursorView(cursor) for cursor in @activeEditSession.getCursors()
+    @addSelectionView(selection) for selection in @activeEditSession.getSelections()
+    @activeEditSession.on 'add-cursor', (cursor) => @addCursorView(cursor)
+    @activeEditSession.on 'add-selection', (selection) => @addSelectionView(selection)
 
-    for selection in @activeEditSession.getSelections()
-      @addSelectionView(selection)
+    @prepareForScrolling()
+    @setScrollPositionFromActiveEditSession()
 
-    @activeEditSession.on 'add-cursor', (cursor) =>
-      @addCursorView(cursor)
-
-    @activeEditSession.on 'add-selection', (selection) =>
-      @addSelectionView(selection)
+    @renderLines()
+    @activeEditSession.on 'screen-lines-change', (e) => @handleRendererChange(e)
 
   destroyEditSessions: ->
     session.destroy() for session in @editSessions
@@ -421,7 +418,6 @@ class Editor extends View
     @scrollView.scrollLeft(@activeEditSession.scrollLeft ? 0)
 
   saveActiveEditSession: ->
-    @activeEditSession.setCursorScreenPosition(@getCursorScreenPosition())
     @activeEditSession.setScrollTop(@scrollTop())
     @activeEditSession.setScrollLeft(@scrollView.scrollLeft())
 
@@ -678,8 +674,9 @@ class Editor extends View
   getCursorViews: ->
     new Array(@cursorViews...)
 
-  removeAllCursorViews: ->
+  removeAllCursorAndSelectionViews: ->
     cursorView.remove() for cursorView in @getCursorViews()
+    selectionView.remove() for selectionView in @getSelectionViews()
 
   getCursor: (index) -> @activeEditSession.getCursor(index)
   getCursors: -> @activeEditSession.getCursors()
@@ -705,6 +702,9 @@ class Editor extends View
     index ?= @selectionViews.length - 1
     @selectionViews[index]
 
+  getSelectionViews: ->
+    new Array(@selectionViews...)
+
   getSelection: (index) -> @activeEditSession.getSelection(index)
   getSelections: -> @activeEditSession.getSelections()
   getSelectionsOrderedByBufferPosition: -> @activeEditSession.getSelectionsOrderedByBufferPosition()

src/app/selection-view.coffee

@@ -15,6 +15,7 @@ class SelectionView extends View
     @regions = []
     @selection.on 'change-screen-range', => @updateAppearance()
     @selection.on 'destroy', => @remove('ignore')
+    @updateAppearance()
 
   updateAppearance: ->
     @clearRegions()
@@ -54,6 +55,6 @@ class SelectionView extends View
   getScreenRange: ->
     @selection.getScreenRange()
 
-  remove: (ignore) ->
+  remove: ->
     @editor.removeSelectionView(this)
     super