Might be worth looking at WP default-widgets.php Tom as there is a custom menu widget included in WP. I can use this to show my primary menu. However,like you said it won’t work with user sections.
Also, I ave noticed that “send sections to default editor” option is having no effect.
How is this option meant to work. If I type anything in normal content area, switch back to user sections and try that option it tells me there is already content in the default editor via a pop-up warning.