https://learn.microsoft.com/ru-ru/dotnet/api/system.windows.forms.control.clientrectangle?view=netframework-4.8.1
Control.ClientRectangle Property (System.Windows.Forms) | Microsoft Learn
Gets the rectangle that represents the client area of the control.
property systemwindows formscontrolmicrosoftlearn
https://learn.microsoft.com/en-us/dotnet/api/system.windows.forms.control.clientrectangle?view=netframework-4.8.1&redirectedfrom=MSDN
Control.ClientRectangle Property (System.Windows.Forms) | Microsoft Learn
Gets the rectangle that represents the client area of the control.
property systemwindows formscontrolmicrosoftlearn