C#

public class SafeLabel : Label
{
   delegate void SetString(string text);
   delegate string GetString();
   override public string Text
   {
      set
      {
         if(InvokeRequired)
         {
            SetString setTextDel = delegate(string text)
                                           {base.Text = text;};
            Invoke(setTextDel,new object[]{value});
         }
         else
            base.Text = value;
      }
      get
      {
         if(InvokeRequired)
         {
            GetString getTextDel = delegate(){return base.Text;};
            return (string)Invoke(getTextDel,null);
         }
         else
            return base.Text;
      }
   }
}

From MSDN:

When a thread other than the creating thread of a control tries to access one of that control's methods or properties, it often leads to unpredictable results. A common invalid thread activity is a call on the wrong thread that accesses the control's Handle property. Set CheckForIllegalCrossThreadCalls to true to find and diagnose this thread activity more easily.

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class MyCrazyLib
{
   private SynchronizationContext syncContext;
   public event EventHandler WorkProgressed;

   public MyCrazyLib(SynchronizationContext eventRaisingSync)
   {
      this.syncContext = eventRaisingSync;
   }

   void DoWorkInBackground()
   {
      ThreadPool.QueueUserWorkItem(MyWorkMethod);
   }

   void MyWorkMethod(object state)
   {
      // Pretend we do some work here...
      ...

      // Now raise the event using our synchronization context.
      this.syncContext.Post(delegate(object state)
      {
         this.WorkProgressed(someSender, EventArgs.Empty);
      });
   }
}

// While on the UI thread.
MyCrazyLib lib = new MyCrazyLib(WindowsFormsSynchronizationContext.Current); // We want to raise events on the current UI thread
lib.WorkProgressed += MyHandler;
lib.DoWorkInBackground();

...

void MyHandler(object sender, EventArgs e)
{
   // This will be called on the UI thread! No Invoke required. :)
}

Tech, life, family, faith: Give me a visit.
I'm currently blogging about: Goof around music jam with my brothers (with video)
The apostle Paul, modernly speaking: Epistles of Paul

Judah Himango