svoid jTextPane_adjustTextSizeToFillParentHeight(JTextPane pane, O... _) {
  if (pane == null || getParent(pane) == null || empty(getText(pane))) ret with callF(optPar onDone(_));
  if (jTextPane_shouldDecreaseFontSizeToFillParentHeight(pane))
    jTextPane_shrinkTextSizeToFillParentHeight(pane, _);
  else if (jTextPane_shouldIncreaseFontSizeToFillParentHeight(pane)) swing {
    float size = pane.getFont().getSize2D();
    float newSize = size+1;
    if (boolPar debug(_)) print("new font size: " + newSize);
    setFontSize(pane, newSize);
    awtLater(optPar delay(_, 50), r {
      jTextPane_adjustTextSizeToFillParentHeight(pane, _);
    });
  }
  else
    callF(optPar onDone(_));
}