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    <p>From looking at the source in forms.pas (Delphi 2009), it appears that they create a "master" window in win32 gui apps to allow calls to </p> <ul> <li>TApplication.Minimize</li> <li>TApplication.Restore</li> <li>etc</li> </ul> <p>It appears that messages passed to the <code>Application.Handle</code> are forwarded as appropriate to the <code>MainForm</code>, if it exists. This would allow the app to respond to minimize, etc if the main window has not been created. By modifying the project source you can create a delphi app <em>without</em> a main window. </p> <p>In this case, the <code>TApplication</code> methods will still work, even if you haven't created a main window. Not sure if I'm grasping all of the purposes, but I don't have time to go through all of the TApplication code. </p> <p>Per your questions:</p> <ul> <li><p><strong>Where does it come from?</strong> It is the handle of a window created in <code>TApplication.Create</code></p></li> <li><p><strong>What windows handle is it?</strong> a fake window that every gui delphi app requires as part of the TApplication abstraction</p></li> <li><p><strong>Is it the windows handle of the appliation's main form</strong> No</p></li> <li><p><strong>If its not the handle of application's mainform then what is it?</strong> See above</p></li> <li><p><strong>more importantly: why is it the ultimate parent of every form?</strong> assuming you're right that its the ultimate parent, i assume that it is so because it makes it easy to find all of forms in your application (enumerating the children of this "master" form).</p></li> <li><p><strong>and most important: why does everything go haywire if i try to have a form be unparented</strong> i think because the hidden "master" form is getting system messages that it <em>should</em> pass on to its children and/or the mainform, but can't find the unparented form.</p></li> </ul> <p>Anyway, that's my take on it. You can probably learn more by looking at the TApplication declaration and code in <code>forms.pas</code>. The bottom line from what i see is it is a convenient abstraction.</p> <p>Best regards,</p> <p>Don</p>
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    1. PODelphi: What is Application.Handle?
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    1. USIan Boyd
    1. USDon Dickinson
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    1. COIn Delphi 2007, the VCL changed to default to not having a hidden window, but you can choose the old way too if that helps. The hidden window stopped Windows 7 preview from working properly.
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      1. USmj2008
    2. CO@mj2008: do you have a link for more information regarding this? I'm currently updating a project from C++ Builder 2006 -> C++ Builder 2009, and I believe I'm seeing my Application->Handle ptr as NULL. Is this the case now in Builder 2009? And if so, would using MainForm->Handle be a good substitute?
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      1. USRob Thomas
    3. CO@Rob The Delphi control for this is Application.MainFormOnTaskbar but I don't know if it applies for you. Typically an upgraded app doesn't have this changed.
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