For 1.7 and after, try:
myDiagram.doFocus = function() {
var x = window.scrollX || window.pageXOffset;
var y = window.scrollY || window.pageYOffset;
go.Diagram.prototype.doFocus.call(this);
window.scrollTo(x, y);
}
This will let it focus, but stop the scrolling. It seems to work on Chrome, Firefox, IE11, and iOS Safari