Border: Class uses `string` for `title`, not `ustring`

In addition, strings (both string and ustring) should be initizlied to .Empty and not null.

Fixing this may be a breaking change.

[tig]

Why not adding it in the NStack? Do you want I do that?

I believe:

1. Classes should always explicitly initialize members (so private type foo is BAD and private type foo = bar is good.
2. strings (both string and ustring) should always be initialized to .Empty instead of null.

Changing Nstack to do this encourages bad developer behavior. So no, I don’t think you should do this to NStack.

[tznind]

we cant initialize with a default string.Empty, see the error:

You could do

public TopLevelContainer (Border border, string title = null)
{
    Initialize(Rect.Empty,border, title ?? string.Empty);
}