https://learn.microsoft.com/en-us/dotnet/api/system.windows.forms.control.preferredsize?view=netframework-4.8.1&tree=cete.dynamicpdf.viewer.pdfnavigationpanel.preferredsize
Control.PreferredSize Property (System.Windows.Forms) | Microsoft Learn
Gets the size of a rectangular area into which the control can fit.
property systemwindows formscontrolmicrosoftlearn