SizeChangedEventArgs could not be found are you missing a using directive

Question

i am not able to figure this error out: "SizeChangedEventArgs could not be found are you missing a using directive..."

Here my setup and code:

• using visual studio 2019

• Csharp

• Build .Net Framework 4.8

• using System.Windows

   private void Form1_SizeChanged(object sender, SizeChangedEventArgs e)
    {
        // Retrieve the old size from the event arguments
        var newSize = ((Form)sender).Size;
        var oldWidth = e.PreviousSize.Width;
        var oldHeight = e.PreviousSize.Height;
        var oldSize = new Size(oldWidth, oldHeight);
  
        // Do something with the old size
        Console.WriteLine("Old size: {0}", oldSize);
    }
  

Answer 1

For WinForms, the SizeChanged event gets written like this on my system:

private void Form1_SizeChanged(object sender, EventArgs e)
{

}