How to change style of canvas and what style would I need

[tdk]

I have the following problem:
in my main panel I have an HLayout which contains
* a section stack, with 1 section and
* a tabset
* each tab contains a section stack too

In order for the first section stack (labeled "Serviceportal") to be aligned with the section stacks in the TabSet (labeled "Accepted (1 records)" and "Details") I would like to change the style of the canvas that contains the section stack to that of the TabSet (see attached image):

I tried the following code:

        SectionStackSection sss = new SectionStackSection("Serviceportal");
        sss.setCanCollapse(false);
        sss.addItem(flyingMenu);

        SectionStack ss = new SectionStack();
        ss.setWidth100();
        ss.setHeight100();
        ss.addSection(sss);

        flyingMenuCanvas = new Canvas();
        flyingMenuCanvas.setShowResizeBar(true);
        flyingMenuCanvas.setStyleName("tabSetContainer");
        flyingMenuCanvas.setHeight100();
        flyingMenuCanvas.setWidth("20%");
        flyingMenuCanvas.setShowResizeBar(true);
        flyingMenuCanvas.setVisible(false);
        flyingMenuCanvas.addChild(ss);

The result can be seen in the attached image, ie not what I want.
I tried various variations, like changing the style of the section stack, doing without the canvas, but all to no avail.

My questions:
1. how can I achieve this?
2. what style name do I need to use?

I'm using GWT 2.1 and SmartGWT 2.3.2010-11-28 on Vista x64