At last find the error & fixed.
Opent "js/dnn.js" javascript file, and find the funtion "cursorPos: function(oCtl)". In this function you will find a cod segment like following:
Replace the red-code with green-code. It'll fix the problem. I tested with Firefox and IE, but not complete QA.
Khurram Raza
// Handle text areas.
{
--i;
else if (sTagName == "textarea")var i = oCtl.value.length + 1;var oCaret = document.selection.createRange().duplicate();while (oCaret.parentElement() == oCtl && oCaret.move("character",1) == 1)if (i == oCtl.value.length + 1)
i = -1;
--i;
}