Max line length is preserved when a new buffer is assigned to an editor.

src/app/editor.coffee

@@ -196,7 +196,7 @@ class Editor extends View
     @trigger 'buffer-path-change'
     @buffer.on "path-change.editor#{@id}", => @trigger 'buffer-path-change'
 
-    @renderer = new Renderer(@buffer)
+    @renderer = new Renderer(@buffer, { maxLineLength: @calcMaxLineLength() })
     @renderLines()
     @gutter.renderLineNumbers()
 
@@ -277,13 +277,14 @@ class Editor extends View
   toggleSoftWrap: ->
     @setSoftWrap(not @softWrap)
 
-  setMaxLineLength: (maxLineLength) ->
-    maxLineLength ?=
-      if @softWrap
-        Math.floor(@scroller.width() / @charWidth)
-      else
-        Infinity
+  calcMaxLineLength: ->
+    if @softWrap
+      Math.floor(@scroller.width() / @charWidth)
+    else
+      Infinity
 
+  setMaxLineLength: (maxLineLength) ->
+    maxLineLength ?= @calcMaxLineLength()
     @renderer.setMaxLineLength(maxLineLength) if maxLineLength
 
   createFold: (range) ->
@@ -406,7 +407,6 @@ class Editor extends View
 
   foldSelection: -> @getSelection().fold()
 
-
   undo: ->
     @buffer.undo()
 

src/app/renderer.coffee

@@ -18,10 +18,10 @@ class Renderer
   lastHighlighterChangeEvent: null
   foldPlaceholderLength: 3
 
-  constructor: (@buffer) ->
+  constructor: (@buffer, options={}) ->
     @id = @constructor.idCounter++
     @highlighter = new Highlighter(@buffer)
-    @maxLineLength = Infinity
+    @maxLineLength = options.maxLineLength ? Infinity
     @activeFolds = {}
     @foldsById = {}
     @buildLineMap()