dojox.drawing.Drawing - custom tool to create rectangle with rounded corners

Question

I'm working with dojox.drawing.Drawing to create a simple diagramming tool. I have created a custom tool to draw rounded rectangle by extending dojox.drawing.tools.Rect as shown below -

dojo.provide("dojox.drawing.tools.custom.RoundedRect");
dojo.require("dojox.drawing.tools.Rect");

dojox.drawing.tools.custom.RoundedRect = dojox.drawing.util.oo.declare(

        dojox.drawing.tools.Rect,
        function(options){
        },
        {
          customType:"roundedrect"
        }    
);

dojox.drawing.tools.custom.RoundedRect.setup = {
    name:"dojox.drawing.tools.custom.RoundedRect",
    tooltip:"Rounded Rect",
    iconClass:"iconRounded"
};
dojox.drawing.register(dojox.drawing.tools.custom.RoundedRect.setup, "tool");

I was able to add my tool to the toolbar and use it to draw a rectagle on canvas. Now, I would like to customize the rectangle created by my custom tool to have rounded corners, but I'm not able to figure out how. I have checked the source of dojox.drawing.tools.Rect class as well as it's parent dojox.drawing.stencil.Rect class and I can see the actual rectangle being created in dojox.drawing.stencil.Rect as follows -

_create: function(/*String*/shp, /*StencilData*/d, /*Object*/sty){
        // summary:
        //              Creates a dojox.gfx.shape based on passed arguments.
        //              Can be called many times by implementation to create
        //              multiple shapes in one stencil.
        //
        //console.log("render rect", d)
        //console.log("rect sty:", sty)
        this.remove(this[shp]);
        this[shp] = this.container.createRect(d)
                .setStroke(sty)
                .setFill(sty.fill);

        this._setNodeAtts(this[shp]);
}

In dojox.gfx, rounded corners can be added to a a rectangle by setting r property. With this context, could anybody please provide answers to my following questions?

1. What's the mechanism in dojox.drawing to customize the appearance of rectangle to have rounded corners?
2. In the code snippet above, StencilData is passed to createRect call. What's the mechanism to customize this data? Can the r property of a rectangle that governs rounded corners be set in this data?