Gadget object returned from property is not modified

Modifications to gadget object returned from property are somehow getting reset. For example:

var f = s.foo
f.setValue(3)
console.log(f.value())

the value is still the initial one even though setValue() is called and the value is changed. When value() is called, the value set in setValue is reset to the original.

Looks like QML engine reads from 'foo' property each time some function is called and thus overrides the modified object.