Wait one second in running program

Wait function using timers, no UI locks.

public void wait(int milliseconds)
{
    var timer1 = new System.Windows.Forms.Timer();
    if (milliseconds == 0 || milliseconds < 0) return;

    // Console.WriteLine("start wait timer");
    timer1.Interval = milliseconds;
    timer1.Enabled  = true;
    timer1.Start();

    timer1.Tick += (s, e) =>
    {
        timer1.Enabled = false;
        timer1.Stop();
        // Console.WriteLine("stop wait timer");
    };

    while (timer1.Enabled)
    {
        Application.DoEvents();
    }
}

Usage: just placing this inside your code that needs to wait:

wait(1000); //wait one second

Personally I think Thread.Sleep is a poor implementation. It locks the UI etc. I personally like timer implementations since it waits then fires.

Usage: DelayFactory.DelayAction(500, new Action(() => { this.RunAction(); }));

//Note Forms.Timer and Timer() have similar implementations. 

public static void DelayAction(int millisecond, Action action)
{
    var timer = new DispatcherTimer();
    timer.Tick += delegate

    {
        action.Invoke();
        timer.Stop();
    };

    timer.Interval = TimeSpan.FromMilliseconds(millisecond);
    timer.Start();
}

Is it pausing, but you don't see your red color appear in the cell? Try this:

dataGridView1.Rows[x1].Cells[y1].Style.BackColor = System.Drawing.Color.Red;
dataGridView1.Refresh();
System.Threading.Thread.Sleep(1000);

.Net Core seems to be missing the DispatcherTimer.

If we are OK with using an async method, Task.Delay will meet our needs. This can also be useful if you want to wait inside of a for loop for rate-limiting reasons.

public async Task DoTasks(List<Items> items)
{
    foreach (var item in items)
    {
        await Task.Delay(2 * 1000);
        DoWork(item);
    }
}

You can await the completion of this method as follows:

public async void TaskCaller(List<Item> items)
{
    await DoTasks(items);
}