[Mono-winforms-list] some fixes for tests

[Miguel de Icaza]

Hello,

> I tried make run-test-ondotnet and got some failures. I believe
> that some are due to environment-dependency (like, some tests
> result different depending on desktop themes). On some languages
> those tests would work, but they don't on this Japanese box.
> 
> It still fails at:

I would love to get these changes into the tree, so we can use this as a
baseline of what needs to be fixed on Linux.

Miguel