https://learn.microsoft.com/en-us/dotnet/api/system.windows.forms.textboxbase.hideselection?redirectedfrom=MSDN&view=netframework-4.7.2
TextBoxBase.HideSelection Property (System.Windows.Forms) | Microsoft Learn
Gets or sets a value indicating whether the selected text in the text box control remains highlighted when the control loses focus.
property systemwindows formshideselectionmicrosoftlearn