As described in the title of the comment, with screen protector (though of reputed brand: NILLKIN), the buttons "back" and "research" of Lumia 830 are virtually unusable. Indeed, they do not respond properly, push repeatedly to last they are taken into account. It is already very complicated to use for simple support, but in the case of a hold (display of task manager or Cortana voice search), it is almost impossible mission ... In short, not recommended.
