title: GUI: How can I find out if certain Unicode characters are supported?
body: <p>I noticed that Metal L&amp;F doesn't support certain arrow characters from Unicode, while Nimbus and GTK L&amp;Fs do support them.</p>
  
  <p><em>Unsupported characters are just displayed as: <code>...</code></em></p>
  
  <p>Can I</p>
  
  <ol>
  <li>either look up (manually), which L&amp;F supports which Unicode chars,</li>
  <li>or find it out at runtime?</li>
  </ol>
  
  <p><strong>EDIT:</strong> Or, should it only depend on the L&amp;F's default font, my question perhaps should be:<br>
  <em>"how do I find out, which Java font supports which Unicode characters?"</em></p>