The ASPxPopupControl contains IDs of objects that can invoke a default popup window within the ASPxPopupControl.PopupElementID property. Use the GetCurrentPopupElementIndex method to get an index of the last object that invoked the default window within the ASPxPopupControl.PopupElementID list. If the window was not shown at all, the method returns the 0 (zero).
You can get the object that invoked the default window using the GetCurrentPopupElement method.
To get the index of the ID of the object that invoked a window from the ASPxPopupControl.Windows collection, use the GetWindowCurrentPopupElementIndex method. The index specifies the zero-based position of the object's ID within the window's PopupWindow.PopupElementID property.