Develop Reference

UI not updating while looping through IP Addresses

I have a simple work to do, On button click it will get all Network IP addresses from a range, loop through them and put the active in a list. While performing the process a panel will be shown on which ip address will be displayed that is being checked. Code runs fine but form hangs up, application go to not responding and ip address not displayed even panel is not shown. how to do that?
my code is:
private void btnAutoSearch_Click(object sender, EventArgs e)
{
panel_Search.Visible = true; // Not Working
Cursor.Current = Cursors.WaitCursor;
string ipBase = getIPAddress();
string[] ipParts = ipBase.Split('.');
ipBase = ipParts[0] + "." + ipParts[1] + "." + ipParts[2] + ".";
for (int i = 1; i < 255; i++)
{
string ip = ipBase + i.ToString();
Ping p = new Ping();
PingReply pingresult = p.Send(ip, 100);
if (pingresult.Status == IPStatus.Success)
{
lstIPs.Add(ip);
lblConnecting.Text = ip; // Not Working
}
}
GridConn.Rows.Clear();
foreach (string s in lstIPs)
{
Device obj = new Device();
obj.IPAddress = s;
lblConnecting.Text = s;
int vSMSLimit = 0;
int.TryParse(txtSMSLimit.Text, out vSMSLimit);
obj.SMSLimit = 0;
if (obj.ConnectToHostServer())
{
obj.SendConnectionMessage();
obj.ReceiveConnectionMessage();
MyDevices.lst.Add(obj);
GridConn.Rows.Add(true, obj.IPAddress, obj.PhoneModel, obj.PhoneStatus, obj.SoftwareVersion);
}
}
Cursor.Current = Cursors.Default;
panel_Search.Visible = false;
}

The issue is that the UI must be updated from the 'Main' thread (always called UI thread), but if you do other processing on this thread then the UI itself will lock up. So you should put long running process onto another thread.
This will cause the problem however that this thread cannot update the UI, as it is not the Main/UI thread. So then you have to invoke the UI thread yourself to update it.
Luckily there is simple way of doing this using the BackgroundWorker class in C# which can help you a lot. But you need to separate out your UI and background tasks.
//Define worker
BackgroundWorker myBGWorker;
//Initalise worker and start it from your button
private void btnAutoSearch_Click(object sender, EventArgs e)
{
panel_Search.Visible = true; // Not Working
Cursor.Current = Cursors.WaitCursor;
myBGWorker = new BackgroundWorker()
//This method will execute your processing on a background thread
myBGWorker.DoWork += new DoWorkEventHandler(bgw_DoWork);
//This method will execute when your background worker finishes
//It runs on the Main/UI thread
myBGWorker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bgw_RunWorkerCompleted);
//This method will execute when the background thread wants to update the progress
//It runs on the Main/UI Thread
myBGWorker.ProgressChanged += new ProgressChangedEventHandler(bgw_ProgressChanged);
//Tell it we will be reporting progress
myBGWorker.WorkerReportsProgress = true;
//Start!
myBGWorker.RunWorkerAsync()
}
private void bgw_DoWork(object sender, DoWorkEventArgs e)
{
string ipBase = getIPAddress();
string[] ipParts = ipBase.Split('.');
ipBase = ipParts[0] + "." + ipParts[1] + "." + ipParts[2] + ".";
for (int i = 1; i < 255; i++)
{
string ip = ipBase + i.ToString();
Ping p = new Ping();
PingReply pingresult = p.Send(ip, 100);
if (pingresult.Status == IPStatus.Success)
{
lstIPs.Add(ip);
//Below reports the progress. The number shouuld represent the percentage of process, the object can be anything you want
double percentDone = (100.0 / 255.0) * i;
e.ReportProgress(Convert.ToInt32(percentDone), ip);
}
}
}
private void bgw_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
lblConnecting.Text = e.UserState as string;
}
private void bgw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
if (e.Cancelled)
MessageBox.Show("Operation was canceled");
else if (e.Error != null)
MessageBox.Show(e.Error.Message);
else
{
GridConn.Rows.Clear();
foreach (string s in lstIPs)
{
Device obj = new Device();
obj.IPAddress = s;
lblConnecting.Text = s;
int vSMSLimit = 0;
int.TryParse(txtSMSLimit.Text, out vSMSLimit);
obj.SMSLimit = 0;
if (obj.ConnectToHostServer())
{
obj.SendConnectionMessage();
obj.ReceiveConnectionMessage();
MyDevices.lst.Add(obj);
GridConn.Rows.Add(true, obj.IPAddress, obj.PhoneModel, obj.PhoneStatus, obj.SoftwareVersion);
}
}
Cursor.Current = Cursors.Default;
panel_Search.Visible = false;
}
}

Desktop applications use one single thread to handle UI, and event handlers run synchronously on the UI thread, that is why form hangs, because it cannot handle other UI interactions while the event handler is running.
Best practice is that event handlers take UI thread for very short time.
When you need to perform long running tasks because of user interaction, you should perform the task in another thread, you should not use the UI thread for long running tasks.
You can use BackgroundWorker to move the task to another thread, but it is better to use asynchronous event handlers.
For example:
private async void myButton_Click(object sender, EventArgs e)
{
await PerformLongRunningTaskAsync();
//TODO: update UI after completing task
await Task.Run(() => PerformLongRunningTaskSynchronously());
//TODO: update UI after completing task;
}
private async Task PerformLongRunnigTaskAsync() {
//TODO: implement this async method
}
private void PerformLongRunningTaskSynchronously() {
//TODO: implement this synchronus method
}
Your code should be something like this:
private async void btnAutoSearch_Click(object sender, EventArgs e)
{
panel_Search.Visible = true; // Not Working
Cursor.Current = Cursors.WaitCursor;
string ipBase = getIPAddress();
string[] ipParts = ipBase.Split('.');
ipBase = ipParts[0] + "." + ipParts[1] + "." + ipParts[2] + ".";
for (int i = 1; i < 255; i++)
{
string ip = ipBase + i.ToString();
Ping p = new Ping();
PingReply pingresult = await p.SendPingAsync(ip, 100);
if (pingresult.Status == IPStatus.Success)
{
lstIPs.Add(ip);
lblConnecting.Text = ip; // Not Working
}
}
GridConn.Rows.Clear();
foreach (string s in lstIPs)
{
Device obj = new Device();
obj.IPAddress = s;
lblConnecting.Text = s;
int vSMSLimit = 0;
int.TryParse(txtSMSLimit.Text, out vSMSLimit);
obj.SMSLimit = 0;
if (await Task.Run(() => obj.ConnectToHostServer())
{
await Task.Run(() => obj.SendConnectionMessage());
await Task.Run(() => obj.ReceiveConnectionMessage());
MyDevices.lst.Add(obj);
GridConn.Rows.Add(true, obj.IPAddress, obj.PhoneModel, obj.PhoneStatus, obj.SoftwareVersion);
}
}
Cursor.Current = Cursors.Default;
panel_Search.Visible = false;
}

Here is how i did the work thanks to Brian Rogers,
private void btnAutoSearch_Click(object sender, EventArgs e)
{
backgroundWorker1.WorkerSupportsCancellation = true;
if (backgroundWorker1.IsBusy != true)
{
// Start the asynchronous operation.
backgroundWorker1.RunWorkerAsync();
}
}
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
BackgroundWorker worker = sender as BackgroundWorker;
for (int j = 1; j <= 10; j++)
{
if (worker.CancellationPending == true)
{
e.Cancel = true;
break;
}
else
{
Cursor.Current = Cursors.WaitCursor;
panel_Search.Location = new Point(380, 72);
// Perform a time consuming operation and report progress.
string ipBase = getIPAddress();
string[] ipParts = ipBase.Split('.');
ipBase = ipParts[0] + "." + ipParts[1] + "." + ipParts[2] + ".";
for (int i = 1; i < 255; i++)
{
string ip = ipBase + i.ToString();
Ping p = new Ping();
PingReply pingresult = p.Send(ip, 100);
if (pingresult.Status == IPStatus.Success)
{
lstIPs.Add(ip);
lblConnecting.Text = ip;
//listBox1.Items.Add(ip);
}
}
GridConn.Rows.Clear();
foreach (string s in lstIPs)
{
Device obj = new Device();
obj.IPAddress = s;
lblConnecting.Text = s;
int vSMSLimit = 0;
int.TryParse(txtSMSLimit.Text, out vSMSLimit);
obj.SMSLimit = 0;
if (obj.ConnectToHostServer())
{
obj.SendConnectionMessage();
obj.ReceiveConnectionMessage();
MyDevices.lst.Add(obj);
GridConn.Rows.Add(true, obj.IPAddress, obj.PhoneModel, obj.PhoneStatus, obj.SoftwareVersion);
}
}
Cursor.Current = Cursors.Default;
panel_Search.Location = new Point(333, 252);
}
}
}

Multithread using backgroundworker and event handler

I'm developing a sample program to connect multiple device using backgroundworker. Each device connected will be add to the list as new object. After finished connecting all the devices, i wanted to add an event handler for each connected devices. The problem that i'm facing now is the event handler doesn't firing at all. Below are the sample codes.
The Connect click button event :
private void btnConnect_Click(object sender, EventArgs e)
{
using (BackgroundWorker m_oWorker = new BackgroundWorker())
{
m_oWorker.DoWork += delegate (object s, DoWorkEventArgs args)
{
int iIpStart = 0;
int iIpEnd = 0;
string strIp1 = string.Empty;
string strIp2 = string.Empty;
list.Clear();
string[] sIP1 = txtIpStart.Text.Trim().ToString().Split('.');
string[] sIP2 = txtIpEnd.Text.Trim().ToString().Split('.');
iIpStart = Convert.ToInt32(sIP1[3]);
iIpEnd = Convert.ToInt32(sIP2[3]);
strIp1 = sIP1[0] + "." + sIP1[1] + "." + sIP1[2] + ".";
strIp2 = sIP2[0] + "." + sIP2[1] + "." + sIP2[2] + ".";
Ping ping = new Ping();
PingReply reply = null;
int iIncre = 0;
int iVal = (100 / (iIpEnd - iIpStart));
for (int i = iIpStart; i <= iIpEnd; i++)
{
Thread.Sleep(100);
string strIpconnect = strIp1 + i.ToString();
Console.Write("ip address : " + strIpconnect + ", status: ");
reply = ping.Send(strIpconnect);
if (reply.Status.ToString() == "Success")
{
if (ConnectDevice(strIpconnect))
{
strLastDevice = strIpconnect + " Connected";
isconnected = true;
}
else
{
isconnected = false;
}
}
else
{
isconnected = false;
}
m_oWorker.ReportProgress(iIncre);
iIncre = iIncre + iVal;
}
m_oWorker.ReportProgress(100);
};
m_oWorker.ProgressChanged += new ProgressChangedEventHandler(m_oWorker_ProgressChanged);
m_oWorker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(m_oWorker_RunWorkerCompleted);
m_oWorker.WorkerReportsProgress = true;
m_oWorker.WorkerSupportsCancellation = true;
m_oWorker.RunWorkerAsync();
}
}
ConnectDevice function method. Connected device will be added to the list :
protected bool ConnectDevice(string sIP)
{
try
{
NewSDK sdk = new NewSDK();
if (sdk.Connect() == true)
{
list.Add(new objSDK { sdk = sdk, ipaddress = sIP });
return true;
}
else
{
}
}
catch() {}
return false;
}
the Backgroundworker :
void m_oWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
//If it was cancelled midway
if (e.Cancelled)
{
lblStatus.Text = "Task Cancelled.";
}
else if (e.Error != null)
{
lblStatus.Text = "Error while performing background operation.";
}
else
{
lblStatus.Text = "Task Completed...";
btnListen.Enabled = true;
}
}
void m_oWorker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
//Here you play with the main UI thread
progressBar1.Value = e.ProgressPercentage;
lblStatus.Text = "Processing......" + progressBar1.Value.ToString() + "%";
if (isconnected)
{
listBox2.Items.Add(strLastDevice);
string[] ssplit = sDeviceInfo.Split(';');
foreach (string sword in ssplit)
{
listBox1.Items.Add(sword);
}
}
}
The function to attached event :
private void RegisterEvent()
{
foreach (objSDK obj in list)
{
obj.sdk.OnTransaction += () =>
{
listBox1.Items.Add("ip : " + obj.IP + " transaction");
};
}
}

You have declared m_oWorker as a local variable. I'm guessing this was a mistake ( the m_ prefix should only be used for class member variables)?
Also, you declared it within a using statement, meaning that it that the framework will call Dispose() on it at the end of the using block. Even if you held on to a reference to it (and I don't think you do) it still means its resources will be deallocated, which is probably why it isn't handling any events.

I try another workaround by using thread and task and work perfectly. Thanks for all response

Different behaviors when instantiated from button or timer in c#

I have a function called getMessages that can be called by a Button click (using the RelayCommand trigger) or that is called in a timer every 15s.
The desired behavior is:
webservice > deserialize answer > system notification > updatelistview > insert localDB
But when the function is called by the timer the updatelistview is not done. Why does this happen if the function is the same and works perfectly in the button command?
CODE:
// Get messages for the logged in user
public async void getMessages()
{
try
{
List<FriendGetMessage> msg = new List<FriendGetMessage>();
var response = await CommunicationWebServices.GetCHAT("users/" + au.idUser + "/get", au.token);
if (response.StatusCode == HttpStatusCode.OK) // If there are messages for me.
{
var aux = await response.Content.ReadAsStringAsync();
IEnumerable<FriendGetMessage> result = JsonConvert.DeserializeObject<IEnumerable<FriendGetMessage>>(aux);
if (result != null)
{
foreach (var m in result)
{
msg.Add(m);
}
//MsgList=msg;
foreach (var f in Friends)
{
if (f.msg == null || f.msg.Count() == 0)
{
f.msg = new ObservableCollection<Messages>();
}
foreach (var mess in msg)
{
if (mess.idUser == f.idUser)
{
Messages mm = new Messages();
mm.received = mess.message;
mm.timestamp = "Received " + mess.serverTimestamp;
mm.align = "Right";
// Add to the friend list.
f.msg.Add(mm);
// Add to Local DB
InsertMessage(null, au.idUser.ToString(), f.idUser, mess.message, mess.serverTimestamp);
var notification = new System.Windows.Forms.NotifyIcon()
{
Visible = true,
Icon = System.Drawing.SystemIcons.Information,
BalloonTipIcon = System.Windows.Forms.ToolTipIcon.Info,
BalloonTipTitle = "New Message from " + f.name,
BalloonTipText = "Message: " + mess.message,
};
// Display for 5 seconds.
notification.ShowBalloonTip(5);
// The notification should be disposed when you don't need it anymore,
// but doing so will immediately close the balloon if it's visible.
notification.Dispose();
}
}
}
counterChat = 1; // resets the counter
}
}
else {
counterChat = counterChat * 2;
}
//var sql = "select * from chat";
//var respo = GetFromDatabase(sql);
OnPropertyChanged("Friends");
}
catch (Exception e)
{
MessageBox.Show("GetMessages: " + e);
Debug.WriteLine("{0} Exception caught.", e);
}
}
CODE TIMER:
public void chatUpdate()
{
_timerChat = new DispatcherTimer(DispatcherPriority.Render);
_timerChat.Interval = TimeSpan.FromSeconds(15);
_timerChat.Tick += new EventHandler(timerchat_Tick);
_timerChat.Start();
}
public void timerchat_Tick(object sender, EventArgs e)
{
if (counterChat != incChat)
{
incChat++;
}
else
{
getMessages();
OnPropertyChanged("Friends");
incChat = 0;
}
}
ADDED - I've also tried this and didn't worked (it seems that is some kind of concurrency problem to the ObservableCollection called Friends (is a friendslist) each friend has an ObservableCollection of messages (is a chat))
public void chatUpdate()
{
_timerChat = new DispatcherTimer(DispatcherPriority.Render);
_timerChat.Interval = TimeSpan.FromSeconds(15);
_timerChat.Tick += new EventHandler(timerchat_Tick);
_timerChat.Start();
}
public async void timerchat_Tick(object sender, EventArgs e)
{
if (counterChat != incChat)
{
incChat++;
}
else
{
Application.Current.Dispatcher.Invoke((Action)async delegate { await getMessages(); });
incChat = 0;
}
}
Best regards,

I think you need to make the timer handler be an async method as follows:
public async void timerchat_Tick(object sender, EventArgs e)
{
if (counterChat != incChat)
{
incChat++;
}
else
{
await getMessages();
OnPropertyChanged("Friends");
incChat = 0;
}
}
This way OnPropertyChanged("Friends") is guaranteed to fire after the work in getMessages is done.
The methods need to change to:
DispatcherTimer _timerChat = new DispatcherTimer(DispatcherPriority.Render);
_timerChat.Interval = TimeSpan.FromSeconds(15);
_timerChat.Tick += new EventHandler(timerchat_Tick);
_timerChat.Start();
public async void timerchat_Tick(object sender, EventArgs e)
{
//...
await getMessages();
//...
}
public async Task getMessages()
{
try
{
// ... your code here
string result = await response.Content.ReadAsStringAsync();
// .... rest of your code
}
catch (Exception e)
{
MessageBox.Show("GetMessages: " + e);
}
}

It is solved. The problem was in my ViewModels I was opening multiple threads and sometimes the right one would update the UI and sometimes no.
Thanks for all the answers.

how to release thread is required in multiple thread?

As title, how to release thread is required in multiple thread ?
Ex : I have 5 thread is waiting. I only want thread position 3 is released
I use autoresetevent/manualresetevent/monitor.wait and monitor.pulse but all release thread follow FIFO
help me !!!
UPDATED:
This is form1:
private BackgroundWorker[] threadArray;
public static ManualResetEvent _manualResetEvent = new ManualResetEvent(false);
private void btn_Start_Scraping_Click(object sender, EventArgs e)
{
threadArray = new BackgroundWorker[listView_Site.Items.Count];
for (var f = 0; f < listView_Site.Items.Count; f++)
{
threadArray[f] = new BackgroundWorker();
threadArray[f].DoWork += new DoWorkEventHandler(BackgroundWorkerFilesDoWork);
threadArray[f].RunWorkerCompleted += new RunWorkerCompletedEventHandler(BackgroundWorkerFilesRunWorkerCompleted);
threadArray[f].ProgressChanged += new ProgressChangedEventHandler(BackgroundWorkerFilesProgressChanged);
threadArray[f].WorkerReportsProgress = true;
threadArray[f].WorkerSupportsCancellation = true;
threadArray[f].RunWorkerAsync(listView_Site.Items[f].Tag.ToString());
}
}
private void BackgroundWorkerFilesDoWork(object sender, DoWorkEventArgs e)
{
....// all above code is fine
requestCaptcha = (HttpWebRequest)WebRequest.Create(uriCaptchaPage);
requestCaptcha.Pipelined = true;
requestCaptcha.KeepAlive = true;
requestCaptcha.AllowAutoRedirect = false;
//request.Proxy = null;
requestCaptcha.Timeout = 60000;
requestCaptcha.Headers.Add(HttpRequestHeader.AcceptEncoding, "gzip,deflate");
requestCaptcha.CookieContainer = sessionID;
request.ServicePoint.Expect100Continue = false;
requestCaptcha.Method = "GET";
requestCaptcha.Referer = uriloginPage.AbsoluteUri;
//get response.
responseCaptcha = (HttpWebResponse)requestCaptcha.GetResponse();
Stream imagestream = responseCaptcha.GetResponseStream();
if (imagestream != null)
{
Image image = Image.FromStream(imagestream);
if (Directory.Exists(Application.StartupPath + "\\Captcha") == false)
{
Directory.CreateDirectory(Application.StartupPath + "\\Captcha");
}
switch (responseCaptcha.ContentType)
{
case "image/jpeg":
{
saveLocation += ".jpg";
if (File.Exists(saveLocation))
{
File.Delete(saveLocation);
}
image.Save(saveLocation,ImageFormat.Jpeg);
break;
}
case "image/gif":
{
saveLocation += ".gif";
if (File.Exists(saveLocation))
{
File.Delete(saveLocation);
}
image.Save(saveLocation, ImageFormat.Gif);
break;
}
case "image/png":
{
saveLocation += ".png";
if (File.Exists(saveLocation))
{
File.Delete(saveLocation);
}
image.Save(saveLocation, ImageFormat.Png);
break;
}
}
//show form2 to enter captcha
lock (_lockObj)
{
if (Application.OpenForms.OfType<frmCaptchaQuestion>().Any() == false)
{
DoOnUIThread(delegate()
{
_formCaptchaQuestion.CreatePanelCaptcha(uriloginPage, saveLocation,idHomePage);
_formCaptchaQuestion.Show();
});
}
else
{
DoOnUIThread(() => _formCaptchaQuestion.CreatePanelCaptcha(uriloginPage, saveLocation,idHomePage));
}
}
//wait and get captcha from form2 and only run thread is required
//this is my problem <<<<========================================
lock (_lockObj)
{
//_manualResetEvent.WaitOne(30000);
//_manualResetEvent.Reset();
//if (clsValueStatic.CaptchaText != null)
//{
// foreach (var id in clsValueStatic.CaptchaText)
// {
while (!_go)
{
Monitor.Wait(_lockObj);
}
// }
//}
}
requestCaptcha = (HttpWebRequest)WebRequest.Create(uriActionLoginPage);
requestCaptcha.Pipelined = true;
requestCaptcha.KeepAlive = true;
requestCaptcha.AllowAutoRedirect = false;
//request.Proxy = null;
requestCaptcha.Timeout = 60000;
requestCaptcha.Headers.Add(HttpRequestHeader.AcceptEncoding, "gzip,deflate");
requestCaptcha.CookieContainer = sessionID;
request.ServicePoint.Expect100Continue = false;
requestCaptcha.Method = "GET";
}
Form2:
private void textBoxCaptcha_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Enter)
{
var textBox = sender as TextBoxX;
if (textBox != null)
{
clsValueStatic.CaptchaText = textBox.Text.Trim();
textBox.Parent.Parent.Dispose();
frmScrapingAnalysis._manualResetEvent.Set();
}
}
}
PS : Form1 have 1 button to start multiple backgroundworker and show form2 then all backgroundworker wait to get text captcha of textbox from form2
my way want when user enter text of backgroundworker is shown on form2 then only the backgroundworker is released. All other backgroundworker still wait

Cross thread problem?

My error
Cross-thread operation not
valid: Control 'MailTree' accessed
from a thread other than the thread it
was created on.
with my code
My idea is when SaveMail method has finish store 1 mes then add this mes to listview.
private delegate int SaveMailDelegate(ImapX.Message mes);
public int SaveMail(ImapX.Message mess)
{
if (!File.Exists("D:\\" + Username + "\\" + MailTree.SelectedNode.Text + "\\" + mes.MessageUid.ToString() + ".eml"))
{
mess.Process();
mess.SaveAsEmlToFile("D:\\" + Username + "\\" + MailTree.SelectedNode.Text + "\\", mes.MessageUid.ToString()); //Store messages to a Location
}
// mes.MessageUid=mess.MessageUid;
return 1;
}
Mime EncodingMail(string NodeName,string focusitem)
{
Mime m = new Mime();
m=Mime.Parse("D:\\" + Username+ "\\"+NodeName+"\\"+focusitem+".eml");
return m;
}
private void AddMesToMailList()
{
ListViewItem item = new ListViewItem();
Mime m = EncodingMail(MailTree.SelectedNode.Text, mes);
item.Text = mes.MessageUid.ToString();
item.SubItems.Add(m.MainEntity.Subject);
ReturnMime(m);
if (mailfromname != null)
item.SubItems.Add(mailfromname);
else item.SubItems.Add(mailfrom);
item.SubItems.Add(m.MainEntity.Date.ToString());
item.SubItems.Add(mailfrom);
MailList.Items.Add(item);
}
private void SaveMailDone(IAsyncResult iar)
{
SaveMailDelegate del = iar.AsyncState as SaveMailDelegate;
if (del != null)
{
int result = del.EndInvoke(iar);
AddMesToMailList();
}
}
private void MailTree_AfterSelect(object sender, System.Windows.Forms.TreeViewEventArgs e)
{
MailList.Items.Clear();
for (int i = 0; i < client.Folders.Count; i++)
{
(ContextMenuListView.Items[1] as ToolStripMenuItem).DropDownItems[i].Click += new EventHandler(MainForm_Click);
}
if (MailTree.SelectedNode.Text == Username)
{
webBrowser1.Visible = false;//webBrowser1.DocumentText = "Hello Baby";
AttachmentList.Visible = false;
groupBox1.Visible = false;
}
else
{
webBrowser1.Visible = true;
groupBox1.Visible = true;
try
{
messages = client.Folders[MailTree.SelectedNode.Text].Search("ALL", false); // Search mail in your choossen Folder
AmoutOfMail = messages.Count(); //Amout of Mail in this Folder
for (int i = 0; i < AmoutOfMail; i++)
{
mes=messages[i];
SaveMailDelegate del = new SaveMailDelegate(this.SaveMail);
del.BeginInvoke(mes, new AsyncCallback(this.SaveMailDone), del);
}
}
catch (Exception)
{ }
}
}

You cannot directly access a control from another thread, you will have to invoke it.
private delegate void ControlCallback(string s);
public void CallControlMethod(string text)
{
if (control.InvokeRequired)
{
ControlCallback call = new ControlCallback((s) =>
{
// do control stuff
});
control.Invoke(call, new object[] { text });
}
else
{
// do control stuff
}
}

you can't access the UI on a different thread than what it was created on. From inside your secondary thread (the one that runs your callback handler) you will need to call Form.BeginInvoke to register a method that will be run on the UI thread. From that method you can update your UI controls

I think AddMesToMailList() is trying to modify the view elements but it is on a wrong thread.
Try something like this
void AddMesToMailList()
{
if (this.InvokeRequired)
{
this.BeginInvoke(new Action(AddMesToMailList));
return;
}
// do stuff that original AddMesToMailList() did.
}
EDIT:
SaveMail is a little complicated as it has a return value but you can try this
public int SaveMail(ImapX.Message mess)
{
if(this.InvokeRequired)
{
return (int) this.Invoke(
new Func<ImapX.Message, int>( m => SaveMail(mess)) );
}
else
{
if (!File.Exists(#"D:\" + Username + "\\" + MailTree.SelectedNode.Text + "\\" + mes.MessageUid.ToString() + ".eml"))
{
mess.Process();
mess.SaveAsEmlToFile(#"D:\" + Username + "\\" + MailTree.SelectedNode.Text + "\\", mes.MessageUid.ToString()); //Store messages to a Location
}
// mes.MessageUid=mess.MessageUid;
return 1;
}
}