C# Maximize button | full code (will maximized if it is normal and go back to normal if pressed again)

FormMain.cs

// Maximise button (when clicked)
private void buttonMaximise_Click(object sender, EventArgs e)
{
  if (this.WindowState == System.Windows.Forms.FormWindowState.Normal) // if the forms state is normal (not maximised or minimised) then..
  {
    this.WindowState = FormWindowState.Maximized; // Tells windows this application should be maximised
  }
  else if (this.WindowState == System.Windows.Forms.FormWindowState.Maximized) // if the forms state is maximised then..
  {
    this.WindowState = FormWindowState.Normal; // Tells windows this application should be in the normal state (not maximised or minimised)
  }
}

Works perfectly - thanks for sharing