Do I need to learn C++ for WPF?

Hi,

I have been coding with WPF since it was release. I used to work with C++ and DirectX but very long time ago(Many years ago)

Is there any feature that could not accomplish with C# WPF?

I used the decompiler to take a look at the Expression Blend code and found that ther's some code. It is really C++ + C#

Do I need to refresh my C++?

I would like to tweak up my skills into advance skills. I am expert on 3DSMAX but I forgot my C++ and directx.

I am not planing to implement any 3D app.

Best Regards,

Weera