Dojo GFX widgets displaying float-like behaviour instead of correct positioning

I'm using Dojo GFX to do some simple drawing, but having a problem with IE 7/8 (switching browsers is not an option).

If I create a div, set up a surface and draw some rects, they draw correctly relative to the div, so far so good.

However, what I want to do is create a widget, something with an embedded 'surface' that draws based on some widget-specific data. As such, I have a widget that contains a div, and I draw into this div. When I do that, the rects I create behave as if they are responding to a float:right, appearing in order they are created and ignoring the 'x' parameter.

I assume that this behaviour is something to do with CSS, but I haven't got to the bottom of it yet. Any ideas or solutions gratefully appreciated!

Updates:

• I've disabled all stylesheets and I am not using style attributes. No difference to the behaviour.
• I've inspected the markup that gets generated using IE8 dev tools. Apart from the different location of the containing div, the only difference I can see is that the v:roundrect elements have no child elements when created against the widget div, but they do have empty elements like stroke when created against the div referenced by ID.
• Reading back through the docs, a difference I can see that might be responsible is that the postCreate method where I am doing my drawing is manipulating a div that has not been added to the dom yet, whereas drawing on a hardcoded div is done when it does exist. Maybe the difference in rendering is something to do with this? Is there a specific lifecycle function which is appropriate to draw in for widgets?

It seems that if you are going to use Dojo GFX and draw on DOM elements that are created as part of a widget in IE7/8, you must actually do the drawing in an override of the startup() method.

Drawing in the postCreate() method causes incorrect rendering resembling a float: left.