.NET (Core and Framework)

string name="myProgName"+Environment.UserName;
Mutex m=new Mutex(false, name);
if (myMutex.WaitOne(1,true)) {
   ... this is my first instance
} else {
   ... I already have an instance running
}

using System;
using System.Windows.Forms;
 
class MainForm : Form
{
  static void Main()
  {
    Application.EnableVisualStyles();
    Application.Run(new MainForm());
  }
 
  MainForm()
  {
    FormBorderStyle = FormBorderStyle.None;
 
    Button btn = new Button();
    Controls.Add(btn);
    btn.Text = "&Exit";
    btn.Click += delegate(object sender, EventArgs e)
    {
      Close();
    };
  }
}

PhoenixHawk wrote:

Is there a control I can user for this

PhoenixHawk wrote:

I have to write this control from scrath by myself?