attributes to a table throught the Table Wizard or manually in HTML mode. The problem is that the table rendering will be not affected in Design mode of RadEditor - no matter these properties are set or not.
The problem is due to that the cellpadding and cellspacing attributes gets overriden by the RadEditor styles, which are used to nicely format that tables and show the dashed table borders in Design mode:
The padding css property overrides the cellpadding and cellspacing attributes.
To fix the problem set the ContentAreaCssFile property of RadEditor to point to your own css file and define your own table td and table th classes by skipping the padding property: