Linea21

see : https://codepen.io/mlewand/pen/oeaZrV

CKEDITOR.replace( 'editor1', {
    extraPlugins: 'colorbutton,font',
    on: {
        afterPasteFromWord: function( evt ) {
            // Clone the filter, so that it's based on current editor filter settings.
            // Note that this function is added in CKE 4.7.3.
            var filter = evt.editor.filter.clone(),
                fragment = CKEDITOR.htmlParser.fragment.fromHtml( evt.data.dataValue ),
                writer = new CKEDITOR.htmlParser.basicWriter();

            // Disallow certain styles.
            filter.disallow( 'span{font-family,color,font-size}' );

            // Process, and overwrite evt.data.dataValue.
            filter.applyTo( fragment );
            fragment.writeHtml( writer );
            evt.data.dataValue = writer.getHtml();
        }
    }
} );

And this code, to handle event :

CKEDITOR.on("instanceReady", function(ev) {
  var editor = ev.editor;
  editor.on("focus", function(ev) {
    alert("focused!");
  });
});