" The combination that works is to call frame.setResizable(true) in setup() and then to use frame.setSize(w,h) in draw().  "

To handle the 'height(0) cannot be <= 0' message drop this into setup():

Edit: woops, the int had to be placed inside the event handler

frame.addComponentListener(new ComponentAdapter() {
   public void componentResized(ComponentEvent e) {
     int minHeight = 50;//your preferred minimum height
     if(e.getSource()==frame) { if (frame.getHeight() < minHight) frame.setSize(frame.getWidth(), minHeight); }
   }
 } );