[Starkit] corruption of starkits by double access

[Steve Blinkhorn]

How can I prevent write-enabled starkits from being corrupted by being
accessed a second time whilst already being accessed?   We are seeing
this as an occasional problem on Windows, where a user "loses" an open
window behind another application, and blithely double-clicks again.

We can't find what sort of corruption is going on, because the starkit
then will not unwrap.

--
Steve Blinkhorn <steve at prd.co.uk>