function insertTag(startTag, endTag, textareaId, tagType) {
        var field = document.getElementById(textareaId);
        field.focus();
        
        if (window.ActiveXObject) {
                var textRange = document.selection.createRange();            
                var currentSelection = textRange.text;
        } else {
                var startSelection   = field.value.substring(0, field.selectionStart);
                var currentSelection = field.value.substring(field.selectionStart, field.selectionEnd);
                var endSelection     = field.value.substring(field.selectionEnd);
        }
        
        
        if (window.ActiveXObject) {
                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
                field.value = startSelection + startTag + currentSelection + endTag + endSelection;
                field.focus();
                field.setSelectionRange(startSelection.length + startTag.length, startSelection.length + startTag.length + currentSelection.length);
        }      
}