Int32EditBox in DataTemplate keydown event handled by parent

In the following DataTemplate I'm not able to put in a manual value into the Int32EditBox at runtime. Outside of the DataTemplate I can see using Snoop that it handles the KeyDown value as it should, but inside the DataTemplate the keydown it is handled by the parent, in this case an override of the ItemsControl.

Is there a solution to get data into the Int32EditBox through the keyboard instead of only the spinner while inside a DataTemplate, part of an ItemsControl override?

Exceprt from the code:

<GridViewColumn locExt:XAMLResourceSource.ResourceProvider="{locExt:XLIFFResProvider ResourceLocator=props:Resources.SequencePlayer}"
                Width="50"
                Header="{locExt:Resource Start_At}">
                <GridViewColumn.CellTemplate>
                    <DataTemplate>
                        <StackPanel Orientation="Horizontal">
                            <RadioButton GroupName="StartInstructionGroup" Visibility="{Binding Path=HasChildren, Converter={StaticResource boolNegationToVisibilityConverter}}" IsChecked="{Binding IsStartInstruction}"/>
                            <editors:Int32EditBox SpinnerVisibility="Visible" Visibility="{Binding Path=IsGroup, Converter={StaticResource boolToVisibilityConverter}}" Maximum="{Binding TotalSteps}" Minimum="1" Value="{Binding Path=StartCycle, Mode=TwoWay}">
                                <editors:Int32EditBox.IsEnabled>
                                    <MultiBinding Converter="{StaticResource booleanAndConverter}">
                                        <Binding Path="IsActive" />
                                        <Binding Path="HasChildren" />
                                    </MultiBinding>
                                </editors:Int32EditBox.IsEnabled>
                            </editors:Int32EditBox>
                        </StackPanel>
                    </DataTemplate>
                </GridViewColumn.CellTemplate>
            </GridViewColumn>