Fix renderers' z positions

a

Source/render/GroupRenderer.swift

@@ -68,6 +68,12 @@ class GroupRenderer: NodeRenderer {
         }) {
             renderers = updatedRenderers
         }
+
+        var parent: NodeRenderer = self
+        while let parentRenderer = parent.parentRenderer {
+            parent = parentRenderer
+        }
+        parent.calculateZPositionRecursively()
     }
 
     override func replaceNode(with replacementNode: Node) {

Source/render/NodeRenderer.swift

@@ -282,6 +282,10 @@ class NodeRenderer {
         }
     }
 
+    func calculateZPositionRecursively() {
+        calculateZPosition(self)
+    }
+
     private func applyClip(in context: CGContext) {
         guard let node = node() else {
             return
@@ -358,3 +362,17 @@ extension NodeRenderer: AnimationObserver {
     }
 
 }
+
+@discardableResult fileprivate func calculateZPosition(_ nodeRenderer: NodeRenderer?, currentIndex: Int = 0) -> Int {
+    nodeRenderer?.zPosition = currentIndex
+    let tag = nodeRenderer?.node()?.tag.first
+    if let groupRenderer = nodeRenderer as? GroupRenderer {
+        var i = currentIndex + 1
+        for child in groupRenderer.renderers {
+            let tag = child.node()?.tag.first
+            i = calculateZPosition(child, currentIndex: i)
+        }
+        return i
+    }
+    return currentIndex + 1
+}

Source/views/MacawView.swift

@@ -178,8 +178,6 @@ open class MacawView: MView, MGestureRecognizerDelegate {
     }
 
     override open func draw(_ rect: CGRect) {
-        calculateZPosition(renderer)
-
         context.cgContext = MGraphicsGetCurrentContext()
         guard let ctx = context.cgContext else {
             return
@@ -192,22 +190,11 @@ open class MacawView: MView, MGestureRecognizerDelegate {
         guard let renderer = renderer else {
             return
         }
+        renderer.calculateZPositionRecursively()
         ctx.concatenate(layoutHelper.getTransform(renderer, contentLayout, bounds.size.toMacaw()))
         renderer.render(in: ctx, force: false, opacity: node.opacity)
     }
 
-    @discardableResult private func calculateZPosition(_ nodeRenderer: NodeRenderer?, currentIndex: Int = 0) -> Int {
-        nodeRenderer?.zPosition = currentIndex
-        if let groupRenderer = nodeRenderer as? GroupRenderer {
-            var i = currentIndex + 1
-            for child in groupRenderer.renderers {
-                i = calculateZPosition(child, currentIndex: i)
-            }
-            return i
-        }
-        return currentIndex + 1
-    }
-
     public final func findNodeAt(location: CGPoint) -> Node? {
         guard let ctx = context.cgContext else {
             return .none