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copied!<p>First of all, the problem to avoid "cross-thread operation was not valid" is use <a href="http://msdn.microsoft.com/en-us/library/zyzhdc6b.aspx" rel="nofollow">Invoke</a> on controls. You cannot use a control from a different thread.</p> <p>About the second issue, I would implement it in the following way. This is a minimum background worker implementation with cancel support.</p> <pre><code>using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Text; using System.Windows.Forms; namespace WindowsFormsApplication5 { public partial class Form1 : Form { public Form1() { InitializeComponent(); // Set the background worker to allow the user to stop the process. backgroundWorkerStopCheck.WorkerSupportsCancellation = true; backgroundWorkerStopCheck.DoWork += new DoWorkEventHandler(backgroundWorkerStopCheck_DoWork); } private void backgroundWorkerStopCheck_DoWork(object sender, DoWorkEventArgs e) { try { for (int i = 0; i < 50; i++) { if (backgroundWorkerStopCheck.CancellationPending) { // user cancel request e.Cancel = true; return; } System.Threading.Thread.Sleep(100); } } finally { InvokeEnableStartButton(); } } private void buttonStart_Click(object sender, EventArgs e) { //disable start button before launch work buttonStart.Enabled = false; // start worker backgroundWorkerStopCheck.RunWorkerAsync(); } private void buttonStop_Click(object sender, EventArgs e) { // Tell the backgroundWorker to stop process. backgroundWorkerStopCheck.CancelAsync(); } private void InvokeEnableStartButton() { // this method is called from a thread, // we need to Invoke to avoid "cross thread exception" if (this.InvokeRequired) { this.Invoke(new EnableStartButtonDelegate(EnableStartButton)); } else { EnableStartButton(); } } private void EnableStartButton() { buttonStart.Enabled = true; } } internal delegate void EnableStartButtonDelegate(); } </code></pre> <p>About passing arguments to the worker, you can pass any object in the <code>RunWorkerAsync()</code> method, and its reveived in the <code>backgroundWorkerStopCheck_DoWork</code> method:</p> <pre><code> ... backgroundWorkerStopCheck.RunWorkerAsync("hello"); ... private void backgroundWorkerStopCheck_DoWork(object sender, DoWorkEventArgs e) { string argument = e.Argument as string; // argument value is "hello" ... } </code></pre> <p>Hope it helps.</p>

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