// textAndColors = a list of Color objects and strings/chars
// Note: This functions changes the BACKGROUND colors
// (not the text, which remains black).
static JTextPane showColoredText(L textAndColors) {
  ret showColoredText(textAndColors, "Colored Text");
}

static JTextPane showColoredText(L textAndColors, S title) {
  JFrame jf = new JFrame(title);
  Container cp = jf.getContentPane();

  new JTextPane pane;
  showColoredText_fillPane(pane, textAndColors);

  cp.add(new JScrollPane(pane), BorderLayout.CENTER);

  jf.setSize(500, 600);
  centerFrame(jf);
  jf.setVisible(true);
  ret pane;
}

static void showColoredText_fillPane(JTextPane pane, L textAndColors) {
  pane.setText("");
  Color color = Color.white;
  for (O x : textAndColors) {
    if (x instanceof Color)
      color = (Color) x;
    else
      showColoredText_appendToTextPane(pane, color, String.valueOf(x));
  }
}

static void showColoredText(JTextPane pane, L textAndColors) {
  showColoredText_fillPane(pane, textAndColors);
}
  
static void showColoredText_appendToTextPane(JTextPane pane, Color color, S text) ctex {
  Document doc = pane.getStyledDocument();
  SimpleAttributeSet set = new SimpleAttributeSet();
  StyleConstants.setFontFamily(set, "Courier");
  StyleConstants.setBold(set, true);
  StyleConstants.setFontSize(set, 14);
  StyleConstants.setBackground(set, color);
  doc.insertString(doc.getLength(), text, set);
}

Began life as a copy of #1001522