The simple example would be
private void Form2_Paint(object sender, PaintEventArgs e)
{
GraphicsPath path = new GraphicsPath();
path.AddEllipse(150f, 150f, 300f, 300f);
e.Graphics.FillPath(Brushes.AliceBlue, path);
Region rgn = new Region(path);
e.Graphics.Clip = rgn;
this.Region = rgn;
path.Dispose();
rgn.Dispose();
}
This is not draggable. You need to implement that functionality. Same way close, minimize buttons has to be add.