We have used dojo extensively in an environment where many complex dialogs are overlayed on a single base page. Dojo is used in both the base page as well as the dialogs. The dialogs have all been constructed with iframes which are created and destroyed dynamically. A major drawback to this approach was that the memory leak, particulary with IE6, was so bad that the application choked after a relatively short time.

After some painstaking investigation, I finally figured out that the 'onunload' event was not being triggered in IE when the iframe was torn down. Our solution has been to handle the dialog close in the following sequence:

1. Set 'src' property of the iframe to 'javascript:false'. This triggers the 'onunload'.
2. Set a brief timeout to process the iframe teardown.

It is also important to ensure that any circular references between the iframe window and the main window are cleaned up.

Our work relates to dojo 0.4, so I'm not sure at this stage how it affects 0.9. My guess is that the same issue exists. I know there's some tickets relating to this sort of problem (#1144). Maybe it's just an education issue rather than something that needs to be fixed in dojo.