title: Can't prevent `touchmove` from scrolling window on iOS
body: <p>We are trying to scroll an element on our iOS web app while preventing the window itself from scrolling. We are capturing the <code>touchmove</code> event on the window, scrolling the element programmatically and (trying to) prevent the window itself from scroll by calling <code>preventDefault</code> on the event.</p>
  
  <p>Unfortunately this doesn't work in Mobile Safari. The window continues to scroll underneath our element. The issue sounds exactly like the Webkit bug described in <a href="https://bugs.webkit.org/show_bug.cgi?id=163207" rel="noreferrer">https://bugs.webkit.org/show_bug.cgi?id=163207</a>, but that issue was supposedly fixed in iOS 10.3 whereas I am running 11.3.</p>
  
  <p>Catching <code>touchforcestart</code> and calling <code>preventDefault</code> does seem to prevent scrolling of the window, but we are calling it in <code>touchstart</code>, which seems to be "too late" since the window still scrolls. Scrolling is only prevented next time <code>touchstart</code> is called.</p>
  
  <p>Any ideas about what is going on? We are baffled since this is clearly a bug but it seems to have been fixed some time ago.</p>