title: tk.Text: Tag Font
body: <p>Is there a way to get a proper <code>Font</code> instance out of a tag, so I can change just the size? I know I can dump it in <code>tk.font.Font</code> but that seems really inefficient.</p>
  <pre><code>for tag in self.tag_names():
      #I need `f` to be a Font instance, not just a string
      f = self.tag_cget(tag, 'font')
  </code></pre>