CSS: Disable text selection highlighting

When working with touch & mouse events to drag html elements, I've occasionally resorted to disabling clicking/touching on child elements by doing something like this:

elem.onmousedown = function(e){ return false; };
elem.onselectstart = function(){ return false; };

But sometimes you want to be able to interact with those child elements... I found some nice CSS over here that prevents text & element highlighting when you're dragging with a mousemove or a touchmove event:

p {
  -webkit-user-select: none;
  -khtml-user-select: none;
  -moz-user-select: none;
  -o-user-select: none;
  user-select: none;
}