C#

FormA.cs
private void Form1_Load(object sender, System.EventArgs e)
{
  Form frmB = new FormB();
  frmB.MdiParent = this;
  frmB.Show();			
}
 
FormB.cs
private void btnAccessFormA_Click(object sender, System.EventArgs e)
{
   //I have created a method called "test". I can't access that method either. And 
   // it got public access.
   Form frmA = new FormA();					
   //This bit of code doesn't work. Cause the object(frmA) i created is referin to null.
// frmA.button1.Visible = true;
// frmA.button2.Visible = true;
// frmA.button3.Visible = true;
// frmA.button4.Visible = true;
// frmA.button5.Visible = true;
// frmA.button6.Visible = true;
}

FormB.cs
private void btnAccessFormA_Click(object sender, System.EventArgs e)
{
   // Get your parent form, which is FormA in this case and access your
   // button since you have set it as public.
   this.MdiParent.button1.Visible = true;
}

((FormA)this.MdiParent).button1.Visible = true;

textBox1.Text = DateTime.Now.ToString("hh:mmtt");