title: Allow entry in QLineEdit only within range of QDoubleValidator
body: <p>I have a set of <code>QLineEdits</code> that are supposed to accept double values within a certain range, (e.g., -15 to 15). </p>
  
  <p>I have something along these lines when setting up each:</p>
  
  <pre><code>lineEdit-&gt;setValidator(new QDoubleValidator(minVal, maxVal, 5, lineEdit));
  </code></pre>
  
  <p>Ideally, the line edits would work such that only values in range can be entered. When I tried this out, I noticed that only numbers could be typed, as desired, but that they could still go out of range. </p>
  
  <p>How can I dynamically force the input to fit into the range (e.g., if range is -15 to 15 and user types a 1, then attempts to type a 9, it doesn't work/display the 9...but typing 1 and then 2 does work/display the 2.) ?</p>
  
  <p>Do I need to connect and call the <code>validate()</code> function somewhere?</p>