create a new attribute in Mendix studio Pro and drop down

HI,    1/ with mendix studio we have de content box to create a new attribute, but with mendix studio pro I don’ t find it.  2/ Why with mendix studionwe use the drop down in widget and for mendix studio pro we need to use reference selector ?   
1 answers

1/ I don’t know exactly what you mean with “Content box” But I can assure you that if it is available in Studio, it should be available in Studio Pro

2/ because Studio is citizen developer focussed, Mendix made the choice to make is easy for modeling. A reference selector will in the end render as dropdown and thus a citizen (non-tech) developer will find it easier to model a dropdown for both technical scenarios; enumeration (attribute)  and reference selection (association)

While studio Pro has a longer history of existing, aiming for the developer and the more technical citizen developer. A dropdown (Select a enum value for attribute) is technical a complete different widget then a reference selector (selecting a vlue form a referenced object) 

History defined that Studio Pro still has 2 different widgets. Studio is in this case a step ahead of Studio Pro