ArcGIS Pro 2.7 API Reference Guide
OnDropDownOpened Method (ComboBox)

ArcGIS.Desktop.Framework.Contracts Namespace > ComboBox Class : OnDropDownOpened Method
Invoked when the combo box's drop-down list is opened.
Syntax
protected internal virtual void OnDropDownOpened()
Protected Friend Overridable Sub OnDropDownOpened() 
Requirements

Target Platforms: Windows 10, Windows 8.1

See Also

Reference

ComboBox Class
ComboBox Members