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  • @NebbishHacker
    Your suggestion on using getModified was "spot on", shame on me ;-)

    Here's my latest code including a random 'drawString` to check that the override is now OK. Seems that it's perfect for me now.

    Ofcourse it requires some bookkeeping of the m variable if you change to a complete different screen.

    var m=0;
    
    // override drawString function to:
    // - allocate proper line spacing between successive lines (here 5 pixels)
    // - clear the area where the previous drawString was displayed
    g._ds = g.drawString;
    g.drawString = function(s,x,y) {
      s=s.toString();
      sa=s.split("\n");
      spacing=5+g.getFontHeight();
    
      g.clearRect(m.x1, m.y1, m.x2, m.y2); // Will clear the precise area affected by the previous drawString calls
    
      g.getModified(true); // Reset modified area
    
      sa.forEach(function(line){    
        //call the original drawString
        g._ds(line,x,y);
        y+=spacing;
      });    
      m=g.getModified(); // save modified area for clearing on next drawString
    };
    
    
    
    // write a random string of random size at random x and y positions
    setInterval(function () {
      g.setFontVector(80*Math.random());
      g.setColor(1,0,0);
      getal=1000*Math.random();
      getal=getal.toFixed(0);
      g.drawString(getal,Math.random()*239,Mat­h.random()*239);
      
    }, 1000);
    
    g.clear();
    
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