How can a WPF StackPanel fill vertically from bottom to top?

Question

I need to be able to fill a stackpanel with buttons but the buttons must appear at the bottom of the stackpanel first and populate upwards<

Answer 1

Or you can rotate the StackPanel 180 degrees to get the buttons to stack from the bottom to the top and then rotating the buttons another 180 degrees to get them right-side-up again:

    
    
        
    

    
    
       
    

    
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