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POModification of Utility Method to Support Multi-Threading
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  1. POModification of Utility Method to Support Multi-Threading
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    copied!<p>I have been given a application to multi-thread and this has been done. All message boxes in this application are correctly called by a single <code>static</code> method in a utility class. This method is:</p> <pre><code>public static void ErrMsg(String strMsg, Exception ex = null) { ... if (ex == null) MessageBox.Show(strMsg, "MyApp", MessageBoxButtons.OK, MessageBoxIcon.Warning); ... } </code></pre> <p>Clearly this does not provide the <code>IWin32Window</code> owner and this is now causing me a problem when I invoke an error message from a background thread-pool thread using this method. The problem is a known one of the message box showing behind my main form. See:</p> <ol> <li><a href="https://stackoverflow.com/questions/3104661/popping-a-messagebox-for-the-main-app-with-backgroundworker-in-wpf">Popping a MessageBox for the main app with Backgroundworker in WPF</a></li> </ol> <p>et al. I could pass in the <code>SynchronisationContext</code> of the current thread to <code>ErrMsg</code> and do </p> <pre><code>synchronizationContext.Send(callback =&gt; MessageBox.Show("Some error message for the user"), null); </code></pre> <p>But there are 700+ calls to this method, the majority of which are on the UI thread and do not cause a problem. My question is: <strong>how can I amend the <code>ErrMsg</code> method so that my message box appears in front reguardless of the current <code>SynchronisationContex</code> and without having to ammend all 700+ calls to the method?</strong></p> <p>Thanks for your time.</p> <hr> <p><strong>Edit.</strong> @Dmitry's idea was great. However, if the active form does not have focus or is an MdiChild form then the <code>Form.ActiveForm</code> will return null. To get around this I use <code>Application.OpenForms.Cast&lt;Form&gt;().Last()</code> to get the last active form, beit MdiChild or whatever. The code is now...</p> <pre><code>Form activeForm = Application.OpenForms.Cast&lt;Form&gt;().Last(); if (ex == null) { activeForm.Invoke(new ShowErrMsg(text =&gt; MessageBox.Show(activeForm, text, "UserCost", MessageBoxButtons.OK, MessageBoxIcon.Warning)), strMsg); } </code></pre>
 

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