We often get questions about why hit testing "doesn't work" around transforms. The short answer is that ancestors don't ask their children to hit test if their own hitTestSelf fails (no point asking your children if they were hit if the hit wasn't inside your bounds).

@csells suggested that it would be nice if a subtree could opt-in to not doing that culling. Obviously that would in general be expensive but it would be less expensive than doing a full tree walk (unless someone opted out the entire tree, obviously). I think we would still avoid doing this ever in the Flutter framework since it's better to adjust the widget hierarchy to not have ancestors of the transformed widget be smaller than that widget, but it might be useful in especially elaborate scenes where that is impractical.

One way to do that would be to have HitTestResult have a flag that says whether to apply the hitTestSelf check. Having to check that flag every step of the walk would itself be not cheap, but the cost (which affects every app) might still be worth it?

Another option might be to have a way for a widget to hook into the hit testing of a far ancestor (e.g. via an inherited widget). That would be better in that it would allow the whole thing to be done as a package. Maintaining paint order correctness would be distinctly non-trivial though (maybe even intractable).

Any other ideas?

cc @goderbauer