private void button1_Click(object sender, EventArgs e)
{
this.Hide(); // Or Close()?
// create new only if not exists
if (!existsAuthorsForm)
{
authorsForm = new AuthorsForm();
authorsForm.Show();
//position right to this
authorsForm.Location = new Point(this.Location.X + this.Size.Width + 10,
this.Location.Y);
existsAuthorsForm = true;
}
authorsForm?.Show();
}