set cursor after button content click in password box wpf

Question

Hi All:
I have a password control box and there is small grid keybaord to enter password, issue is that the moment when i click on the button to enter the password, the cursor deosn't move after password box content
.
How can i set the cursor in the password box after the content got enterted by button click? in my case the cursor is set before the content.

  private void bkletter_Click(object sender, RoutedEventArgs e)  
        {  
            
             ppassword.Password = ppassword.Password + "K";  
             FocusManager.SetFocusedElement(this, ppassword);  
         }  
  
        <PasswordBox Name="ppassword" HorizontalAlignment="Left" Margin="111,50,0,0" FocusManager.IsFocusScope="True"  
                     VerticalAlignment="Top" Height="33" Width="249" PasswordChar="*" FontSize="25" KeyDown="ppassword_KeyDown"   />  
  
  
<Button Content="K" Name="bkletter" Grid.Row="0" Grid.Column="0"   
                        VerticalAlignment="Top" Width="81" Height="44" IsCancel="True" FontSize="28" Background="White" Click="bkletter_Click" >  
                    <Button.Effect>  
                        <DropShadowEffect/>  
                    </Button.Effect>  
                </Button>  

Answer 1

Some articles suggests this code:

var a = new KeyEventArgs( Keyboard.PrimaryDevice, Keyboard.PrimaryDevice.ActiveSource, 0, Key.End )  
{  
    RoutedEvent = Keyboard.KeyDownEvent  
};  
InputManager.Current.ProcessInput( a );  

Add it after FocusManager.SetFocusedElement.