Add a "resized" event

[rmacfadyen]

It would be handy if the resize plug in fired a "resized" event at the end of the resize.

More or less in the dragEndHandler do the following:

function dragEndHandler(evt) {
    CKEDITOR.document.removeListener('mousemove', dragHandler);
    CKEDITOR.document.removeListener('mouseup', dragEndHandler);

    if (editor.document) {
        editor.document.removeListener('mousemove', dragHandler);
        editor.document.removeListener('mouseup', dragEndHandler);
    }
    editor.fire( 'resized' ); // let folks know the resize has finished
}

This would allow clients to persist the size of the editor if they wished to (trying to persist after each individual resize event is too resource intensive).