Pencil tool with Smart Tool
 

Example:
I'm editing volume curves with a Smart Tool on. I have a grouped stereo track (two mono tracks). Pressing Cmd gives me a grabber (finger) to adjust or add volume spots. Adjusting one track (e.g. left) will affect on both grouped volume curves (left+right). If I press Ctrl to use a Pencil tool, drawing only affects another track. Why is that?
If I select Pencil tool only (ST off), drawing affects to both grouped tracks.