Cursor screen position is updated when lines are rewrapped.

spec/atom/editor-spec.coffee

@@ -83,12 +83,14 @@ describe "Editor", ->
         expect(editor.lines.find('.line:eq(8)').text()).toBe ': right.push(current);'
         expect(editor.lines.find('.line:eq(9)').text()).toBe '    }'
 
-      it "changes the max line length when the window size changes", ->
+      it "changes the max line length and repositions the cursor when the window size changes", ->
+        editor.setCursorBufferPosition([3, 60])
         editor.width(editor.charWidth * 40)
         $(window).trigger 'resize'
         expect(editor.lines.find('.line').length).toBe 19
         expect(editor.lines.find('.line:eq(4)').text()).toBe "left = [], right = [];"
         expect(editor.lines.find('.line:eq(5)').text()).toBe "    while(items.length > 0) {"
+        expect(editor.bufferPositionForScreenPosition(editor.getCursorScreenPosition())).toEqual [3, 60]
 
       it "unwraps lines and cancels window resize listener when softwrap is disabled", ->
         editor.toggleSoftWrap()

src/atom/cursor.coffee

@@ -8,6 +8,8 @@ class Cursor extends View
     @pre class: 'cursor idle', style: 'position: absolute;', => @raw ' '
 
   editor: null
+  screenPosition: null
+  bufferPosition: null
 
   initialize: (@editor) ->
     @one 'attach', => @updateAppearance()
@@ -18,6 +20,7 @@ class Cursor extends View
   setScreenPosition: (position) ->
     position = Point.fromObject(position)
     @screenPosition = @editor.clipScreenPosition(position)
+    @bufferPosition = @editor.bufferPositionForScreenPosition(position)
     @goalColumn = null
     @updateAppearance()
     @trigger 'cursor:position-changed'
@@ -29,9 +32,10 @@ class Cursor extends View
   setBufferPosition: (bufferPosition) ->
     @setScreenPosition(@editor.screenPositionForBufferPosition(bufferPosition))
 
-  getBufferPosition: ->
-    @editor.bufferPositionForScreenPosition(@getScreenPosition())
+  refreshScreenPosition: ->
+    @setBufferPosition(@bufferPosition)
 
+  getBufferPosition: -> _.clone(@bufferPosition)
   getScreenPosition: -> _.clone(@screenPosition)
 
   getColumn: ->

src/atom/editor.coffee

@@ -170,6 +170,7 @@ class Editor extends View
       @cursor.bufferChanged(e)
 
     @lineWrapper.on 'change', (e) =>
+      @cursor.refreshScreenPosition()
       { oldRange, newRange } = e
       screenLines = @linesForScreenRows(newRange.start.row, newRange.end.row)
       if newRange.end.row > oldRange.end.row