And call `extern crate std` when the feature is enabled.
I've read this is the good practice on how to do it.
So that the std prelude is no longer included automatically.
There is then less difference between std and and no-std build which
should avoid surprises in the CI when we use things from the prelude.
The downside is that there is a bit of churn in the tests
This is the most stupid policy for popup placement
that we can possibly implement: If we render the
popup as a subsurface in our own window, then just
make sure we move to popup so that it does stay fuilly
within our own window surface.
