AdjustWindowRectEx

[DllImport("user32.dll", SetLastError = true)] [return: MarshalAs(UnmanagedType.Bool)]
public static extern bool AdjustWindowRectEx(
   ref RECT lpRect,
   uint dwStyle,
   [MarshalAs(UnmanagedType.Bool)] bool bMenu,
   uint dwExStyle
);

Microsoft documentation: Link