by Davo Smith.
Damyon - would it be worth seeing if it was possible to replace the 'edit submission' button with a helpful message when the page is viewed whilst 'switch role to student' is enabled? ("You cannot submit assignments when using 'Switch role to ...' - see [link to FAQ] for more details")
I've not looked at the code, so I don't know how difficult this would be, but it comes up often enough that it clearly causes confusion (especially if we assume that those posting on the forums are only a small subset of those who have been caught out by this, and that some people have discovered the answer in the FAQ / forums, but only after quite a bit of head-scratching).