title: WPF, ScrollViewer consuming touch before longpress
body: <p>I'm kinda new to this WPF world.
  And I'm kinda confused on why my scrollview is consuming my touch event.</p>
  
  <p>My current situation is this:</p>
  
  <p>I have this ScrollViewer with an ItemsControl. In this ItemsControl I'm using a Wrappanel to show a number of Rectangles. My ScrollViewer should make it possible to scroll vertically to show the Rectangles that are wrapped downward.
  On each of these Rectangles I made a CustomBehaviour with all kinds of handlers.
  One of these handlers is a 'creatively' made way to handle LongPressGestures.</p>
  
  <p>The problem is as follows, before my longpress is detected by the behaviour, my ScrollViewer is capturing my TouchDevice in its PreviewTouchMove handler.</p>
  
  <p>How can I prevent my ScrollViewer from capturing my TouchDevice too early?
  How can I make sure that I can scroll my ScrollViewer and do my LongPress, DoubleClick (which still works), SingleClick (which still works as well) and other gestures I might add to this custom behaviour?</p>
  
  <p>I've found similar questions on stackoverflow and google that I just not figure out for my specific case.</p>
  
  <p><a href="https://stackoverflow.com/questions/8369040/slider-scrollviewer-in-a-touch-interface-not-working-properly">Something with a CustomThumb</a> &lt;-- This link solves the problem by making a CustomThumb. Can I somehow re-use this for my behaviour? By capturing the TouchDevice early in my behaviour handlers?</p>
  
  <p>If all things fail. Is there an alternative to this ScrollViewer &amp; CustomBehaviour combination?</p>
  
  <hr>
  
  <p>EDIT:</p>
  
  <p>In the meantime. I retried the CustomThumb-method. I got the longpress to work now from my CustomBehaviour while the UIElements (with that behaviour) are located on a ScrollViewer.
  However the scroll functionality of the ScrollViewer still does not work.
  The bounty I added will also be awarded to the person that helps me get that to work properly again (since the answer should lie in the same direction as this CustomThumb solution). </p>