Automatically Resizing Textarea (IE Problem)

I wrote an auto resizing textarea:

function myMax(anumber, another) {
if (anumber > another) {
return anumber;
}
return another;
}

function resizeTextArea(t,minCols,minRows) {
var lines = 0;
if (t.getAttribute("cols") == null) t.setAttribute("cols",minCols);
if (t.getAttribute("rows") == null) t.setAttribute("rows",minRows);
textLine = t.value.split("
");

// get lines of textbox
lines = t.value.split("
").length;

// get longest row of textbox.
var max = 0;

for (i=0;i < textLine.length;i++) {
if (parseInt(textLine[i].length) >
parseInt(t.getAttribute("cols"))) {
lines += Math.floor(parseInt(textLine[i].length) /
parseInt(t.getAttribute("cols"))) ;
}
}
t.setAttribute("rows",myMax(lines+1,minRows));
}

In Firefox this works really fine! But in IE the text area grows very strange. If I add a line, after a while there seems to be a problem with spacing.