Lines remain syntax-highlighted when they are updated.

spec/atom/editor-spec.coffee

@@ -39,6 +39,12 @@ describe "Editor", ->
       line12 = editor.lines.find('.line:eq(11)')
       expect(line12.find('span:eq(1)')).toMatchSelector '.keyword'
 
+    describe "when lines are updated in the buffer", ->
+      it "syntax highlights the updated lines", ->
+        expect(editor.lines.find('.line:eq(0) span:eq(0)')).toMatchSelector '.keyword.definition'
+        buffer.insert([0, 4], "g")
+        expect(editor.lines.find('.line:eq(0) span:eq(0)')).toMatchSelector '.keyword.definition'
+
   describe "cursor movement", ->
     describe ".setCursorPosition({row, column})", ->
       beforeEach ->

src/atom/editor.coffee

@@ -133,12 +133,7 @@ class Editor extends Template
         @cursor.bufferChanged(e)
 
     updateLineElement: (row) ->
-      line = @buffer.getLine(row)
-      element = @getLineElement(row)
-      if line == ''
-        element.html(' ')
-      else
-        element.text(line)
+      @getLineElement(row).replaceWith(@buildLineElement(row))
 
     insertLineElement: (row) ->
       @getLineElement(row).before(@buildLineElement(row))