title: Where to store shadow colors in ThemeData?
body: <p>1- I have a container with a box shadow and that shadow has a different color depending on the theme. Where exactly do I store the shadow color in ThemeData? I stored the container’s color in <code>canvasColor</code> but I am not sure where to put the shadow color. So I can easily do Theme.of(context)...</p>
  
  <p>2- When making separate themes, is it ok if I do <code>return ThemeData(myStuff);</code> instead of doing <code>ThemeData().copyWith(myStuff);</code>? Or is copyWith the recommended way?</p>