title: WPF ZIndex from more parents
body: <p>If i have 2 canvases, one with ZIndex 1 and one with ZIndex 2.</p>
  
  <p>The Canvas with ZIndex 1 has 2 children: 2 canvases, one with ZIndex 4 and one with ZIndex 6.</p>
  
  <p>The Canvas with ZIndex 2 has 2 children: 2 canvases, one with ZIndex 3 and one with ZIndex 5.</p>
  
  <p>And all these canvases has the same dimension and the same starting point, so i will see a single rectangle.</p>
  
  <p>What will be the final order of drawing? 1,2,3,4,5,6 or 1,4,6,2,3,5?</p>
  
  <p>In other words every parent will draw its children based on the ZIndex (so first the parent with ZIndex 1 and after that the parent with ZIndex 2? Or the ZIndex works at global level?</p>