Country and Enhanced selection are contributions so you should contact the contributor if there are bugs with them. There is an issue with checkbox, this is already reported and will be fixed. Selection shows a combobox if I'm not mistaken and it should not be possible _not_ to select anything in it by design.
I'm the main programmer of the Enhanced selection datatype. We use it on all of our portals (both internal and external ones) and we have yet to find an issue with the required option.
If you believe there is an issue, you're welcome to email me the full details at hmelis [at] sckcen [dot] be (preferrably steps how to reproduce the problem).
