function popup_center (page, largeur, hauteur, options) {
	var x = window.screenX;
	if (isFinite(x) == false) {
		x = 0;
	}
	var y = window.screenY;
	if (isFinite(y) == false) {
		y = 0;
	}
	var H = window.outerHeight;
	if (isFinite(H) == false) {
		H = screen.height;
	}
	var L = window.outerWidth;
	if (isFinite(L) == false) {
		L=screen.width;
	}
	var left = Math.round(x + ((L - largeur)/2));
	var top = Math.round(y + ((H - hauteur)/2));
 	win =  window.open(page, null, 'top='+top+', left='+left+', width='+largeur+', height='+hauteur+', '+options);
 	win.focus();
}