https://learn.microsoft.com/en-us/dotnet/api/system.windows.forms.control.allowdrop?view=netframework-4.8.1&redirectedfrom=MSDN
Control.AllowDrop Property (System.Windows.Forms) | Microsoft Learn
Gets or sets a value indicating whether the control can accept data that the user drags onto it.
property systemwindows formscontrolmicrosoftlearn