title: How to find out the current widget size in tkinter?
body: <p>I'm using <em>Python</em> and <em>Tkinter</em>, and I need to know the current dimensions (width, height) of a widget.</p>
  
  <p>I've tried <code>somewidget["width"]</code>, but it returns only a fixed value, and is not updated whenever the widget size changes (e.g. when the window is resized).</p>