I have just tried this , and to my surprise it did nothing
[DllImport("user32.dll")]
public static extern int SendMessage(IntPtr hWnd, int wMsg, IntPtr wParam, IntPtr lParam);
public static void Maximise()
{
System.IntPtr wParam = new System.IntPtr(0xF030);
System.IntPtr lParam = new System.IntPtr(0);
SendMessage(Game1.Instance.Window.Handle, 0x112, wParam, lParam);
}
Which sends a message WM_SYSCOMMAND with a wParam of SC_MAXIMIZE
This should work…