Ability to use Separator line in dropdown field to differentiate higher and lower priority values

[liangsj]

Hi Team, 

Submitting on behalf of customer 

It would be great if we can have dropdown field that allows for a separator so that for properties such as country/region we can set primary countries to be above and the rest to be after the separator line. 

Example 

- United States to be above the line 

then the rest to be after the line