Disabilita html a discesa elemento

disattivare la selezione di testo html

<div 
 style="-moz-user-select: none;
        -webkit-user-select: none;
        -ms-user-select:none;
        user-select:none;
        -o-user-select:none;"
     
 unselectable="on"
 onselectstart="return false;" 
 onmousedown="return false;">
    Blabla
</div>