<!-- more xaml here -->

<ItemsControl ItemsSource="{Binding Items}">
  <ItemsControl.Resources>
    <DataTemplate DataType="{x:Type MyNameSpace:MyType1}">
      <RadioButton />
    </DataTemplate>
    <DataTemplate DataType="{x:Type MyNameSpace:MyType2}">
      <ComboBox  />
    </DataTemplate>
    <DataTemplate DataType="{x:Type MyNameSpace:MyType3}">
      <TextBox />
    </DataTemplate>
  </ItemsControl.Resources>
</ItemsControl>

<!-- more xaml here -->

remark: you arent allowed to give a key to that resources. i suppose the type is kind of key here.

• FocusManager
• Keyboard.Focus
• InputElement.Focus
• InputElement.MoveFocus

what i understand from msdn is that the best way to set the initial focus is the focusmanager. but we encountered two problems where that wont work:

• set initial focus to a button with a commandbinding
• set initial focus to an element defined through a contenttemplate

i did not understand why that is. but i found two strange things: when setting a breakpoint in the ContentRendered-Event you can see the button is visible, but it is disabled. so i understand that i doesnt make sense to set the focus to a disabled element. this seems like a bug to me. another thing i could not understand is when the content of the control is set through a ContentTemplate the Method FrameworkElement.FindName(string elementName) wouldnt find the element. isnt that a bug too? when you inspect the window on screen with scoop u can see all the elements of course.
i tried to use the other focus-methods in various events but none worked. funny thing: if you set the focus and have a breakpoint in the Loaded-Event and just go on after stopping there the focus is correct. Racecondition?

so is there someone who had similar problems? am i wrong with my feeling that these are bugs?

i added an example solution where you can see the sourcecode.