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POC# add-in for application (via COM) freezes when a Control is added to the form?
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copied!<p>I am developing an extension for existing application via <code>COM.</code></p> <p>Current interface of the application to extend allows <strong>to create custom property windows</strong> and use them inside that application.</p> <hr> <p><em>Now, I am using <code>.NET</code> for that purpose and have strange problems:</em></p> <pre><code> extensionForm = new Form(); extensionForm.SetBounds(0, 0, 100, 100); extensionForm.Controls.Add(new Button()); ExApplAPI.AddCustomPropertyWindow(extensionForm.Handle.ToInt32(), "Ololo"); </code></pre> <p>As you can see below, the property sheets <em>actually get extended</em>, but after that something strange starts to happen.</p> <p><img src="https://i.stack.imgur.com/Cntf2.png" alt="enter image description here"></p> <p>Basically, if I switch to <code>Ololo</code> tab, then back to any of other 3 tabs (<code>Attributes</code>, <code>Drawing</code> or <code>Services</code>), <strong>the application freezes.</strong> I also know that the freeze happens inside of some unmanaged code block.</p> <hr> <p>Another interesting fact here is that if I don't write the <code>extensionForm.Controls.Add(new Button())</code> <em>(with or without the Suspend / Resume Layout calls)</em>, <strong>everything works fine.</strong> So, if the recently constructed form has no controls (buttons or any other) on it, <em>it doesn't freeze.</em></p> <p>Here is a <code>Spy++</code> log on the <code>Ololo</code> window right before the freeze (last message is the <code>WM_CTLCOLORBTN</code>, right after that the application became frozen):</p> <p><img src="https://i.stack.imgur.com/NIDSi.png" alt="enter image description here"></p> <hr> <h2>Combining everything together:</h2> <ul> <li>Freezing happens only if I switch from <code>Ololo</code> to some other tab and then switch to the <code>Ololo</code> tab again.</li> <li>Freezing only happens if the integrated form has at least <strong>one control on it,</strong> forms without controls don't freeze.</li> <li>Application is not running any managed code at the moment and is not spending any CPU time.</li> </ul> <p><strong>So - any ideas / similiar problems solved / etc to help me in this case?</strong></p>

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