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POWhy does BackgroundWorker_RunWorkerCompleted not update GUI?
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copied!<p>I already searched the forum but no asked question fits to my problem I think ...</p> <p>I use a BackgroundWorker to handle a very time consuming operation. After this operation finishes a button should be set to enabled so that the user can perform another operation. </p> <p>I'm using WPF and I'm following the MVVM pattern, so I have no direct access to this button. I have to call a method in the BackgroundWorker_RunWorkerCompleted event handler which sets a Property, representing the buttons enabled-state, to true. </p> <p>That all works fine except one thing: The button is only redrawn after I e.g. click into the window (or maximize the window, ...). Thats very annoying and took me the whole day to get rid of this behaviour but I can't find a solution ... </p> <p>The BackgroundWorker_RunWorkerCompleted event handler looks like this:</p> <pre><code> void fileLoadBackgroundWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) { SetButtonToEnabled(); } </code></pre> <p>Has anyone any idea how to fix this issue? </p> <p>Edit:</p> <p>The button is bound to a command: </p> <pre><code><Button Name="btnLoadTargetFile" Command="{Binding Path=LoadTargetCommand}" .../> </code></pre> <p>This command is a RelayCommand as Smith stated in his blog (<a href="http://msdn.microsoft.com/en-us/magazine/dd419663.aspx" rel="nofollow noreferrer">http://msdn.microsoft.com/en-us/magazine/dd419663.aspx</a>) and looks like this:</p> <pre><code>public RelayCommand LoadTargetCommand { get { if (loadTargetCommand == null) { loadTargetCommand = new RelayCommand(param => this.OnRequestLoadFile(BusinessLogic.CustomTypes.TreeType.Target), param => this.CanLoadTarget); } return loadTargetCommand; } set { loadTargetCommand = value; } } </code></pre> <p>this.CanLoadTarget is set to true by the SetButtonToEnabled(); method</p> <p>Edit 2: </p> <p>the following code 'works': </p> <pre><code>fileLoadBackgroundWorker.RunWorkerAsync(argumentList); while(fileLoadBackgroundWorker.IsBusy) System.Windows.Forms.Application.DoEvents(); SetButtonToEnabled(); </code></pre> <p>but that is some sort of really dangerous and ugly code ...</p>

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