[JS] Big bug

<script type="text/javascript">
function insertTag(startTag, endTag, textareaId, tagType) {
        var field  = document.getElementById(textareaId); 
        var scroll = field.scrollTop;
        field.focus();
        
        if (window.ActiveXObject) { // C'est IE
                var textRange = document.selection.createRange();            
                var currentSelection = textRange.text;
                
                textRange.text = startTag + currentSelection + endTag;
                textRange.moveStart("character", -endTag.length - currentSelection.length);
                textRange.moveEnd("character", -endTag.length);
                textRange.select();     
        } else { // Ce n'est pas IE
                var startSelection   = field.value.substring(0, field.selectionStart);
                var currentSelection = field.value.substring(field.selectionStart, field.selectionEnd);
                var endSelection     = field.value.substring(field.selectionEnd);
                
                field.value = startSelection + startTag + currentSelection + endTag + endSelection;
                field.focus();
                field.setSelectionRange(startSelection.length + startTag.length, startSelection.length + startTag.length + currentSelection.length);
        } 

        field.scrollTop = scroll; // et on redéfinit le scroll.
}
function actions(text) {
        text = ' ' + text + '';
        if (document.post.comment_final.createTextRange && document.post.message.caretPos) {
                var caretPos = document.post.comment_final.caretPos;
                caretPos.text = caretPos.text.charAt(caretPos.text.length - 1) == ' ' ? text + '' : text;
                document.post.comment_final.focus();
        } else {
        document.post.comment_final.value  += text;
        document.post.comment_final.focus();
        }
}
</script>