如何在WPF中获取按钮内容以填充宽度

In the following XAML the button will stretch to fit the width of the window, including as you resize the window. However, the TextBlock and blue box are centered. How would you change it so that: 1) the TextBlock is inside the Button, but left justified with the actual Button width (i.e. on the left side of the Window) 2) the Canvas is inside the Button, but right-justified with the actual Button width (i.e. on the right side of the Window)In the following XAML the button will stretch t