If you go to your demo page at https://alfonsoml.blogspot.co.uk/2012/04/placeholder-text-in-ckeditor.html and type some text, then hit undo (control-z or the undo-backarrow) a couple of times, then the "Type here..." placeholder text becomes the editable text in the buffer.
You have to type a bit of text first, to trigger it. Hitting undo to start with is ignored, as it should be.
Possibly you need to do an "editor.resetUndo()" after inserting the text?
If you go to your demo page at https://alfonsoml.blogspot.co.uk/2012/04/placeholder-text-in-ckeditor.html and type some text, then hit undo (control-z or the undo-backarrow) a couple of times, then the "Type here..." placeholder text becomes the editable text in the buffer.
You have to type a bit of text first, to trigger it. Hitting undo to start with is ignored, as it should be.
Possibly you need to do an "editor.resetUndo()" after inserting the text?