Since the user can now swipe the home screen down to dismiss it, doing so instead of tapping on an activity feels more like an alternate way of getting the home screen out of the way instead of canceling what you were doing there. This makes an interaction where the user scrolls through activity list and then swipes it away feel weird, as the user would be moved back to the previously active application instead of the one they just scrolled to.
Fix that by activating the toplevel right away when the user scrolls to it. This doesn't actually bring focus to the window, as it's stolen by phosh's layer-shell surface due to it being keyboard interactive, but it does raise it up and makes it active once the user folds the home screen.
Do it only when not docked, as raising windows when you scroll through the list is not really the expected behavior on multi screen setups.
Right now it's a rather minor thing IMO, but I can imagine this becoming quite a nuisance with !1079 in.