title: Flutter: Detect tapping on one widget and releasing on a different one
body: <p>I want to long press a <strong>first widget</strong> and trigger a function. During the same <code>PointerDownEvent</code> (that is, without removing finger or mouse from the screen) continue and drag the finger or mouse to <strong>a second widget</strong>. This second widget should trigger another function when the so named <code>onPointerUp</code> event happens.</p>
  <p>I was thinking on using <code>GestureDetector</code> instances, but they don't seem to have what I am looking for, maybe I'm wrong. Another option would be using <code>Listener</code> instances and handling on whether their offsets match the pointer's offset. Could this be the solution? I wonder if there is a more straightforward way.</p>
  <p>Something like pressing a key in a phone's keyboard and dragging the finger to select a symbol could be a good example.</p>
  <p><a href="https://i.stack.imgur.com/YsSCK.gif" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/YsSCK.gif" alt="enter image description here" /></a></p>