title: Cursor event handling in python+Tkinter
body: <p>I'm building a code in which I'd like to be able to generate an event when the user changes the focus of the cursor from an Entry widget to anywhere, for example another entry widget, a button...</p>
  <p>So far i only came out with the idea to bind to TAB and mouse click, although if i bind the mouse click to the Entry widget i only get mouse events when inside the Entry widget.</p>
  <p>How can I accomplish generate events for when a widget loses cursor focus?</p>
  <p>Thanks in advance!</p>