DataTrigger

<ListBox>
    <ListBox.Triggers>
        <DataTrigger Binding="{Binding IsListBoxEnabled}" Value="False">
            ...
        </DataTrigger>
    </ListBox.Triggers>
</ListBox>

If you try to add a DataTrigger to the ListBox.Triggers Collection, you will get the following 

exception:

 Triggers collection members must be of type EventTrigger.

Fortunately, there is a simple workaround to allow DataTriggers: using Style.Triggers! 

<ListBox ItemsSource="{Binding KeyFrames}" >
    <ListBox.Style>
        <Style>
            <Style.Triggers>
                <DataTrigger Binding="{Binding IsListBoxEnabled}" Value="False">
                    <DataTrigger.EnterActions>
                        <BeginStoryboard>
                            <Storyboard>
                                <DoubleAnimation To="0.3" 

Storyboard.TargetProperty="Opacity" Duration="0:0:0.400"/>
                            </Storyboard>
                        </BeginStoryboard>
                    </DataTrigger.EnterActions>
                    <DataTrigger.ExitActions>
                        <BeginStoryboard>
                            <Storyboard>
                                <DoubleAnimation To="1" 

Storyboard.TargetProperty="Opacity" Duration="0:0:0.400"/>
                            </Storyboard>
                        </BeginStoryboard>
                    </DataTrigger.ExitActions>
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </ListBox.Style>
</ListBox>

MVVM TextBox Focus

If your are an MVVM enthusiast like me, you may will encounter the following problem: You want to focus a specific textbox from your ViewModel, but you do not have access to your TextBox. So you need some property you can bind to:

   1:  public static class FocusExtension

   2:  {

   3:      public static bool GetIsFocused(DependencyObject obj)

   4:      {

   5:          return (bool)obj.GetValue(IsFocusedProperty);

   6:      }

   7:   

   8:   

   9:      public static void SetIsFocused(DependencyObject obj, bool value)

  10:      {

  11:          obj.SetValue(IsFocusedProperty, value);

  12:      }

  13:   

  14:   

  15:      public static readonly DependencyProperty IsFocusedProperty =

  16:              DependencyProperty.RegisterAttached(

  17:                  "IsFocused", typeof(bool), typeof(FocusExtension),

  18:                  new UIPropertyMetadata(false, OnIsFocusedPropertyChanged));

  19:   

  20:   

  21:      private static void OnIsFocusedPropertyChanged(DependencyObject d,

  22:              DependencyPropertyChangedEventArgs e)

  23:      {

  24:          var uie = (UIElement)d;

  25:          if ((bool)e.NewValue)

  26:          {

  27:              uie.Focus();

  28:          }

  29:      }

  30:  }

There is only one drawback in this solution: If another control gets the focus, the IsTextBoxFocused Property does not change. So if you try to focus the textbox if the property (still) is true, you have to set it to false and fire the PropertyChanged notification before setting it to true.

   1:  private bool _isFocused = false;

   2:  public bool IsTextBoxFocused

   3:  {

   4:      get

   5:      {

   6:          return _isFocused;

   7:      }

   8:      set

   9:      {

  10:          if (_isFocused == value)

  11:          {

  12:              _isFocused = false;

  13:              RaisePropChanged("IsTextBoxFocused");

  14:          }

  15:          _isFocused = value;

  16:          RaisePropChanged("IsTextBoxFocused");

  17:      }

  18:  } 

<TextBox local:FocusExtension.IsFocused="{Binding IsTextBoxFocused}" /> 

If you simply want to set the initial focus to a specific TextBox (or any other control), you can use the FocusManager.FocusedElement property of  any superior layout panel (which contains the TextBox that should be focused)

<Grid x:Name="LayoutRoot" 

      FocusManager.FocusedElement="{Binding 

                       ElementName=myInitialFocusedTextBox}">
    ...
    <TextBox Name="myInitialFocusedTextBox"  />
    ...
</Grid>

Unable to connect to Analysis Services

If you are running multiple instances of Analysis Services on your machine (I am running MSSQLSERVER2008 - which is default instance - and MSSQLSERVER2008R2), you may get the following error when connecting to the non-default instance (via SQL Management Studio):

No connection could be made because the target machine actively refused it 127.0.0.1:2382 (System)

I solved the problem by running the Sql Server Browser as LOCAL SYSTEM instead of NETWORK SERVICE. Open Sql Server Configuration Manager -> Right click 'SQL Server Browser' and open the properties -> Chose 'Local System' as Built-In account in the 'Log on as' tab