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POdrag into another process
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  1. POdrag into another process
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    copied!<p>I am trying to drag an item out into the explorer.<br> The item should result in a file download, so I've used an example I've found on the web to download the file using a <code>CustomDataObject</code> that calls an event when he actually needs the stream, and then my application does the heavy lifting and performs the download.<br> It's been working just fine in a similar Clipboard operation. </p> <p>The actual file download also causes some UI changes in my application. Mostly a "working" icon changing on the form, and also a popup balloon in case of an error. </p> <p>In the clipboard operation I just used <code>InvokeRequired</code> and <code>BeginInvoke</code> when needed, to make sure those UI changes happen on the main thread. In the drag operation, the UI thread is waiting for the return from the <code>DoDragDrop</code>, while the event being raised by the <code>CustomDataObject</code> is being called on a different thread. When I try to call <code>BeginInvoke</code> or <code>Invoke</code> the UI thread is still waiting, and I can't finish the drop. </p> <p>Is there some sample, or a recommended best practice, on how to allow cross-application drag n drop, while accessing the UI of the source application?</p> <h1>UPDATE</h1> <p><a href="http://www.codeproject.com/KB/dotnet/DataObjectEx.aspx" rel="nofollow noreferrer">here</a> is the original CodeProject article with the <code>DataObjectEx</code> I modified for my own use. I just changed the <code>GetFileContents</code> method to call a virtual method which returns a <code>Stream</code> containing the file data, inherited from the class, and overridden that virtual method to get the file from the web. The problem arose when I wanted to change stuff in the UI, while getting the file. As I said earlier - the main UI thread is still "stuck" at the <code>DoDragDrop</code> method call, so I can't invoke it on time to do the UI changes needed by the worker thread before and after downloading the file.</p>
 

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