BackgroundWorker blocking NotifyIcon's ContextMenu

Question

I have a WinForms app with the following (skeleton) code:

namespace MyTrayApp
{
    public class SysTrayApp : Form
    {
        [STAThread]
        public static void Main()
        {
            try
            {
                SysTrayApp app = new SysTrayApp();
                Application.Run();
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private NotifyIcon _trayIcon;
        private ContextMenu _trayMenu;

        private BackgroundWorker _bw = new BackgroundWorker();

        public SysTrayApp()
        {
            _trayMenu = new ContextMenu();
            _trayMenu.MenuItems.Add("Exit", OnExit);

            _trayIcon = new NotifyIcon();
            _trayIcon.Icon = new Icon(SystemIcons.Asterisk, 40, 40);

            _trayIcon.ContextMenu = _trayMenu;
            _trayIcon.Visible = true;

            _bw.WorkerReportsProgress = false;
            _bw.WorkerSupportsCancellation = true;
            _bw.DoWork += new DoWorkEventHandler(bw_DoWork);
            _bw.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bw_RunWorkerCompleted);
            _bw.RunWorkerAsync();
        }

        private void bw_DoWork(object sender, DoWorkEventArgs e)
        {
        // do stuff
        }

        private void bw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            if (e.Cancelled)
            {
            return;
            }
            Thread.Sleep(TimeSpan.FromMinutes(5)); // wait 5 minutes...
            _bw.RunWorkerAsync(); // then run again
        }
    }
}

The problem is that I can only right-click to open the ContextMenu when the app starts up. It seems that once the BackgroundWorker starts sleeping, it somehow blocks the ContextMenu. Thoughts?

Put the Thread.Sleep statement in the DoWork function. That's the function that executes in a background thread. — ZippyV, Aug 13 '13 at 19:30
What do you actually want to achieve? Do you want to execute something in the background every 5 minutes or did you want to use `Thread.Sleep` temporarily to _simulate_ work? — ZippyV, Aug 13 '13 at 19:43

score 3 · Accepted Answer · edited Aug 13 '13 at 19:41

3

Thread.Sleep is executed on the gui(main) thread (http://msdn.microsoft.com/en-us/library/ms171728.aspx) due to the way you've cread the BGW You should use a Timer instead Thread.Sleep 5 minutes.

Timer Class: http://msdn.microsoft.com/en-us/library/system.windows.forms.timer.aspx

edited Aug 13 '13 at 19:41

Peter Ritchie

35,463
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answered Aug 13 '13 at 19:20

Jeroen van Langen

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2

Doesn't this look like a question back? – King King Aug 13 '13 at 19:21
I could write the first parts as comment, the second as answer, i did combine it. – Jeroen van Langen Aug 13 '13 at 19:23
Convince me that the `Sleep` is executed on the GUI thread and you've got yourself at the least an upvote. – kevlar1818 Aug 13 '13 at 19:23
Just execute this: Debug.WriteLine(Thread.CurrentThread.ManagedThreadId); on the Constructor and the bw_RunWorkerCompleted. If the Id's are the same, then it's the same thread. – Jeroen van Langen Aug 13 '13 at 19:24
@KingKing that was when his answer was just "Isn't the Thread.Sleep executed on the gui(main)thread? You should use a Timer instead", which I'm pretty sure SO doesn't think is a good enough answer. Adding a link to the Timer class is *getting* there... – kevlar1818 Aug 13 '13 at 19:29
1

Ultimately, I think my problem is best solved by having a `Timer` trigger my `BackgroundWorker`'s `DoWork`, which is not described in this answer. – kevlar1818 Aug 13 '13 at 19:31
3

More specifically `RunWorkerCompleted` executes on the same thread that created the` BackgroundWorker` object (see reference in answer). – Peter Ritchie Aug 13 '13 at 19:35
as a side fyi [ProgressChanged](http://msdn.microsoft.com/en-us/library/system.componentmodel.backgroundworker.progresschanged.aspx) has the same behavior. – Scott Chamberlain Aug 13 '13 at 19:42

BackgroundWorker blocking NotifyIcon's ContextMenu

1 Answers1