Work around of the accented character suggestion feature in OS X.

On OS X, press and hold `c` could show an accent menu to replace `c` with
accented ones like `ć`, there is no corresponding events in W3C, so we
detected it by checking whether the text in input box are selected (this
is how Chrome implemented this feature).

And also note that IME inputs were handled the same way in Chrome, the
compostion text would be marked as selected and got replaced with final
inputs. However the compostion text won't trigger textInput event, so
it's distinguished by checking whether the hiddenInput's value are
changed by Chrome.

Fixes atom/atom-shell#50.

src/editor.coffee

@@ -88,7 +88,7 @@ class Editor extends View
     @configure()
     @bindKeys()
     @handleEvents()
-    @handleImeEvents()
+    @handleInputEvents()
     @cursorViews = []
     @selectionViews = []
     @pendingChanges = []
@@ -678,10 +678,6 @@ class Editor extends View
 
       @selectOnMousemoveUntilMouseup() unless e.ctrlKey or e.originalEvent.which > 1
 
-    @on "textInput", (e) =>
-      @insertText(e.originalEvent.data)
-      false
-
     unless @mini
       @scrollView.on 'mousewheel', (e) =>
         if delta = e.originalEvent.wheelDeltaY
@@ -697,7 +693,7 @@ class Editor extends View
       else
         @gutter.addClass('drop-shadow')
 
-  handleImeEvents: ->
+  handleInputEvents: ->
     @on 'cursor:moved', =>
       cursorView = @getCursorView()
       @hiddenInput.offset(cursorView.offset()) if cursorView.is(':visible')
@@ -712,6 +708,20 @@ class Editor extends View
       @insertText(selectedText, {select: true, skipUndo: true})
       @hiddenInput.css('width', '1px')
 
+    lastInput = ''
+    @on "textInput", (e) =>
+      # Work around of the accented character suggestion feature in OS X.
+      selectedLength = @hiddenInput[0].selectionEnd - @hiddenInput[0].selectionStart
+      if selectedLength is 1 and lastInput is @hiddenInput.val()
+        position = @getCursorScreenPosition()
+        position.column -= 1
+        @selectToScreenPosition(position)
+
+      lastInput = e.originalEvent.data
+      @insertText(lastInput)
+      @hiddenInput.val(lastInput)
+      false
+
   selectOnMousemoveUntilMouseup: ->
     lastMoveEvent = null
     moveHandler = (event = lastMoveEvent) =>