String ref in Dropdown component

### Description

Using Dropdown component leads to error

### Error Trace (if possible)

Uncaught Error: Element ref was specified as a string (default) but no owner was set. This could happen for one of the following reasons:
1. You may be adding a ref to a function component
2. You may be adding a ref to a component that was not created inside a component's render method
3. You have multiple copies of React loaded

### Solution

Upgrade component to new React guide rules