Dojo How to ColorPalette + TooltipDialog + DropDownButton

Question

I am trying to add a ColorPalette into a TooltipDialog, which in turn is contained inside DropDownButton (dojo 1.3.1) Code:

var paramsContent = new dijit.layout.ContentPane();
var colorPalette = new dijit.ColorPalette();
var tooltipThematic =  new dijit.TooltipDialog({content: paramsContent});

var colorField = new dijit.form.DropDownButton( 
        {label: 'Select Color', 
         dropDown: tooltipThematic
        }
    );

How can I add the colorPalette into tooltipThematic? I did

var tooltipThematic =  new dijit.TooltipDialog(new dijit.ColorPalette())

but then I got this message:

Already registered widget (error message on 1.0)

http://o.dojotoolkit.org/forum/dijit-dijit-0-9/dijit-support/already-registered-widget-error-message

How can I add the ColorPalette into the TooltipDialog?