<TabControl x:Name="tabControl">
            <TabItem Header="Переход (F1)" IsTabStop="False">
<TextBox Grid.Row="1"  x:Name="textBoxF1 " />
</TabItem>
            <TabItem Header="Переход (F2)" IsTabStop="False">
<TextBox Grid.Row="1"  x:Name="textBoxF2 " />
</TabItem>
 </TabControl>

void LogEditWindow_KeyDown(object sender, KeyEventArgs e)
        {
            
            if (e.Key == Key.F1)
            {

                tabControl.SelectedIndex =  0 ;


            }
            if (e.Key == Key.F2)
            {
                tabControl.SelectedIndex =  1 ;
            }

 private void textBoxF2_Loaded(object sender, RoutedEventArgs e)
        {
           if (first.IsSelected)
            {
                (sender as TextBox).Focus();
            }
        }