title: Placing TabView inside NavigationView makes header transparent
body: <p>TabView worked fine for me before i added NavigationView around it.
  Here's a normal behaviour
  <img src="https://cdn-std.droplr.net/files/acc_128373/u66RXj" width="300"></p>
  <p>A problem arises when i add NavigationView around my TabView - when scrolling I see &quot;test&quot; in front of black rectangle.</p>
  <img src="https://cdn-std.droplr.net/files/acc_128373/kKDcKh" width="300">
  <p>I tried setting</p>
  <blockquote>
  <p>UINavigationBar.appearance().backgroundColor</p>
  </blockquote>
  <p>to some opaque color but it just draws another rectangle in front of everything.</p>
  <p>Is there any way to make that black rectangle opaque when using NavigationView around TabView?</p>
  <p>Oh, one more thing.. i tried removing</p>
  <blockquote>
  <p>.edgesIgnoringSafeArea(.top)</p>
  </blockquote>
  <p>which solves the problem but huge white space appears in top area:</p>
  <img src="https://cdn-std.droplr.net/files/acc_128373/uWhCt2" width="300">
  <pre><code>import SwiftUI
  
  struct ContentView: View {
      
      let tabData = [
          TabItem(menuTitle: Text(&quot;item 1&quot;), menuImage: Image(systemName: &quot;heart.fill&quot;), bodyHeadline: Text(&quot;Postnatal recovery&quot;), bodyMeta: Text(&quot;&quot;), tag: 1),
          TabItem(menuTitle: Text(&quot;item 2&quot;), menuImage: Image(systemName: &quot;heart.fill&quot;), bodyHeadline: Text(&quot;Weight loss&quot;), bodyMeta: Text(&quot;&quot;), tag: 2),
      ]
      
      var body: some View {
          NavigationView {
              ZStack {
                  TabView {
                      ForEach(tabData) { tabItem in
                          VStack {
                              VStack {
                                  Rectangle()
                              }
                              .frame(height: 90)
                              .background(Color.yellow)
                              
                              ScrollView {
                                  LazyVStack(spacing: 0) {
                                      ForEach(0...100, id:\.self) { val in
                                          ZStack {
                                              Text(&quot;test&quot;)
                                                  .font(.system(size: 128))
                                          } // ZStack
                                          .background(Color.white)
                                      } // ForEach
                                  }
                              }
                              .background(Color.blue)
                              
                          }
                          
                          .tabItem {
                              tabItem.menuImage
                              tabItem.menuTitle
                                  .foregroundColor(Color.red)
                          }
                          .edgesIgnoringSafeArea(.top)
                      } // ForEach
                      
                  } // TabView
              } // ZStack
          } // NavigationView
      }
  }
  
  struct ContentView_Previews: PreviewProvider {
      static var previews: some View {
          ContentView()
      }
  }
  
  struct TabItem: Identifiable {
      var id = UUID()
      var menuTitle: Text
      var menuImage: Image
      var bodyHeadline: Text
      var bodyMeta: Text
      var tag: Int
  }
  </code></pre>