So we have Arcade in popups now. Sweet. Now once we get popup CSS able to be controlled and be moveable and we're cookin'. 
Kelly Gerrow I love the new ArcGIS Online update. Now for the next major upgrade, allowing programmers to program the popup html would be good because I would make the < > (back/forward) buttons in the upper right larger. Or more discoverable. Users often do not notice them until I show them. Once they are shown usually they are good but for some reason they are not as discoverable as I would have thought. Also they are physically small, and so easy to miss clicking. So maybe these buttons can get revamped too in the next major update. And of course, this scratches the surface. The interface being driven by Arcade would allow it to look and feel like anything, based on attribute data. Unlimited possibilities!
