Occurs before the editor's dropdown (popup window) is closed.
public event ClosingPopupEventHandler PopupClosing
Public Event PopupClosing As ClosingPopupEventHandler
The PopupClosing event's data class is DevExpress.Xpf.Editors.ClosingPopupEventArgs.
The event parameter provides the CloseMode and EditValue properties, allowing you to obtain how the dropdown is being closed and the editor's value, respectively. After the dropdown has been closed, the editor fires the PopupBaseEdit.PopupClosed event.
To prevent an end user from closing a popup, set the event arguments' Cancel and Handled properties to true.