title: In Python3/tkinter how to set the size of a frame relative to its parent window size?
body: <p>In Python3/tkinter is there a simple way to set the size of a <code>ttk.frame</code> as being relative to its parent window size and ensure that it will adjust properly (with all its widgets) on window resize?</p>
  
  <p>As a bit of context, I am trying to <code>pack()</code> a <code>ttk.frame</code> a few pixels smaller than the <code>root</code> window width.</p>