Mark's answer is correct for, but just to make it clearer. Like the question, I was using ZStack{ // Child content } .frame(width: 200, height: 500, alignment: .topLeading) But this doesn't work, presumably because the frame is adding a parent view to the ZStack, and the alignment is not being added directly to the ZStack itself. By taking the following approach of passing the alignment directly to the ZStack at initialisation, I was able to get the expected results with all children position top left. ZStack(alignment: .topLeading) { // Child content } .frame(width: 200, height: 500, alignment: .topLeading)

Thanks for pointing this out, I missed it completely.. Will still be interested to hear why the positioning results change based on where I click in the Rectangle (i.e why repeated clicks in one spat can have .zero translation, whilst repeated clicks in others don't)

(Accidentally posted this as an answer and can't delete). After some more testing, it's not actually just StateObject. If I add this to the view, and then try to print it in the action, the lag is present. @State var test:Bool = false

Also looking for something like this myself. I'm trying to attain the same kind of right hand collapsible sidebar as is used in Xcode.