Hi,
On Menu Item Click event add below Code,
if(Application.OpenForms.Count > 0)
{
bool flag = false;
foreach(Form frm in Application.OpenForms)
{
if(frm.Name == "frmMenu")
{
}
else
{
flag = true;
break;
}
}
if(flag)
{
MessageBox.Show("Kindly close the current Form");
}
else
{
Form2 frm = new Form2();
frm.Show();
}
}
else
{
Form2 frm = new Form2();
frm.Show();
}
hope it helps.