FieldSelect size support

Describe the problem you would like to solve
I am developing a plug-in adding custom fields, and I would appreciate if FieldSelect has size support like the FieldText.

How it is now

Describe the solution you’d like

Additional information
I tried to change the FieldSelect code to add the size attribute, the same way FieldText does, but it didn’t work. Would it be better in issues from pkp/lib repo?