How can Stop if Form Already Open..

Dear,

 

 

How can stop if form already open.

 

For Example i showed my form in panel but when i click  its opening again and again so how can i stop this.. when i click one time should be open if i click second time should be not open again.. 

below my code.. 

 

private void Store_information_button_Click(object sender, EventArgs e)
{
try
{
StoresInformation storeinformation = new StoresInformation();

storeinformation.TopLevel = false;
Showing_Data_panel1.Controls.Add(storeinformation);
storeinformation.FormBorderStyle = System.Windows.Forms.FormBorderStyle.None;
storeinformation.Dock = DockStyle.Fill;
storeinformation.Show();


}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}