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    <p>Try this code</p> <pre><code> Form1 form1 = new Form1(); //Subscribe event here form1.MdiParent = this; form1.Show(); </code></pre> <p>This works for me</p> <p><strike>I don't know why your code doesn't work, I'll get back once I get the answer.</strike></p> <p>Edit: I have got the answer now.</p> <p><code>ISynchronizationInvoke's</code> members (<code>Invoke</code> and <code>BeginInvoke</code>) are implemented by <code>Control</code> class as follows.</p> <ol> <li>Gets context of Thread which created the window.</li> <li>Generate a new window messageId using <code>RegisterWindowMessage</code></li> <li>Encapsulate the delegate we passed as a parameter in <code>ThreadMethodEntry</code> add it into control's internal <code>Queue</code></li> <li>Posts the message to thread's queue with messageId returned by <code>RegisterWindowMessage</code> using <code>PostMessage</code></li> <li>Handles <code>WndProc</code> listens for <code>messageId</code> then De-queues the <code>ThreadMethodEntry</code> and invokes the delegate.</li> </ol> <blockquote> <p>What goes wrong here?</p> </blockquote> <p>Form1 form1 = new Form1(); form1.Show(); form1.MdiParent = this;</p> <p><code>Form.Show</code> somehow results in a call to <code>OnLoad</code> method, that is where <code>OnShown</code> is called Asynchronously using <code>BeginInvoke</code></p> <pre><code>if (base.IsHandleCreated) { base.BeginInvoke(new MethodInvoker(this.CallShownEvent));//reflected code } </code></pre> <p>So before the posted <code>WindowMessage</code> receives you set <code>form1.MdiParent = this;</code> which in turn forces the control to <code>Destroy</code> it's handle and <code>ReCreate</code> new handle.</p> <p><code>DestroyHandle</code> method swallows the posted message by getting it using <code>PeekMessage</code> function, and then enumerates all elements in <code>Queue</code> and sets its state as completed without invoking the delegate but marking it to throw <code>ObjectDisposedException</code>.</p> <pre><code>Form1 form1 = new Form1(); form1.Show(); Action del = () =&gt; { Console.WriteLine("This will never be called");//our custom delegates too fails to be invoked }; var res = form1.BeginInvoke(del); //after some more code form1.EndInvoke(res);//throws `ObjectDisposedException` which was marked previously form1.MdiParent = this; </code></pre> <p>throwing <code>ObjectDisposedException("Control")</code> is actually misleading isn't it?</p> <p>Note: You can fix this easily using <code>Application.DoEvents();</code> before <code>form1.MdiParent = this;</code> since <code>DoEvents</code> process all the pending messages immediately.</p>
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    1. USSriram Sakthivel
    1. USSriram Sakthivel
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    1. COOMG, thank you so much!, cant believe i've been struggling with this thing for a week and the solution was that simple :O
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    2. COOh man, a week is a huge time. but cheers you got it now. I'll let you know why it doesn't work once I found it. Am very curious to know why It doesn't work.
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