+1  A: 

Hi Edward,

There is no property in the ToolBar class which allows you to do this. But you can always override ToolBar's style. Get default style for you theme. Usually that thumb part is called "OverflowGrid". Just remove it or make it hidden.

Hope that answers your question. But I'm wondering why do you want to remove it? Are you sure you need toolbar control there at all? Maybe raw ItemsControl with proper colors will work for you?

Anvaka