Advanced Tab Catch

function setSelectionRange(input,selectionStart,selectionEnd){if(input.setSelectionRange){input.focus();input.setSelectionRange(selectionStart,selectionEnd);}else if(input.createTextRange){var range=input.createTextRange();range.collapse(true);range.moveEnd('character',selectionEnd);range.moveStart('character',selectionStart);range.select();}}
function replaceSelection(input, replaceString, shift) {
    var ie = false;
    var value = input.value;
    if (input.setSelectionRange) {
        var selectionStart = input.selectionStart;
        var selectionEnd = input.selectionEnd;
        var old = value.substring(selectionStart, selectionEnd);
    } else if(document.selection) {
        ie = true;
        var range=document.selection.createRange();
        if (range.parentElement() == input) {
            var selectionStart = input.selectionStart;
            var selectionEnd = input.selectionEnd;
            var old = range.text;
        } else return;
    }
    var isCollapsed = old == '';
    if (!isCollapsed && replaceString == '\t' && (old.indexOf('\n') != -1 || ((!selectionStart || value.charCodeAt(selectionStart - 1) == 10) && (selectionEnd == value.length || value.charCodeAt(selectionEnd) == 10)))) {
        if (selectionStart) selectionStart = value.substring(0, selectionStart + 2).lastIndexOf('\n') + 1 || selectionStart;
        selectionEnd = (value.indexOf('\n', selectionEnd) + 1 || value.length + 1) - 1;
        old = value.substring(selectionStart, selectionEnd).split("\n");
        var i = old.length, a;
        if (!shift) while (i--) {
            a = old[i];
            if (a) old[i] = '\t' + a;
        }
        else while (i--) {
            a = old[i];
            if (a) old[i] = (a.charCodeAt(0) == 9 ? a.substr(1) : a);
        }
        replaceString = old.join('\n');
    }
    if (ie) {
        range.text = replaceString;
        if (isCollapsed) return;
    } else {
        input.value = value.substring(0, selectionStart) + replaceString + value.substr(selectionEnd);
    }
    var end = selectionStart + replaceString.length;
    setSelectionRange(input, (selectionStart != selectionEnd) ? selectionStart : end, end);
}
function stopEvent(e){if(e.preventDefault){e.preventDefault();}if(e.stopPropagation){e.stopPropagation();}e.stopped=true;}
function catchTab(item,e){if(!e)e=window.event;var c=e.keyCode||e.which;if(c==9){var scrollCurrent=item.scrollTop;replaceSelection(item,String.fromCharCode(9),e.shiftKey);stopEvent(e);item.scrollTop=scrollCurrent;return false;}}