https://learn.microsoft.com/ru-ru/dotnet/api/system.web.ui.webcontrols.menu.dynamichoverstyle?view=netframework-4.8.1
Menu.DynamicHoverStyle Property (System.Web.UI.WebControls) | Microsoft Learn
Gets a reference to the Style object that allows you to set the appearance of a dynamic menu item when the mouse pointer is positioned over it.
property systemweb uimenumicrosoftlearn