Scripting API

BasePopupField<TValueType, TValueChoice>

class in UnityEngine.UIElements · UnityEngine.CoreModule · inherits from BaseField<TValueType>

Not in Unity's public API, or in an assembly the coverage doesn't count.
In Tassix

A field that shows its value and picks it from a list of choices in a dropdown menu.

Fields 5

static readonly string arrowUssClassName
static readonly string inputUssClassName
static readonly string labelUssClassName
static readonly string textUssClassName
static readonly string ussClassName

Properties 2

virtual List<TValueChoice> choices { get; set; }
string text { get; }