title: Create a size dependency between views
body: <p>Scenario: I have a activity layout with a viewpager containing multiple fragments and a header view with a dynamic height. The fragments should containe a placeholder with the same height of the header and its content.</p>
  
  <p><img src="https://i.stack.imgur.com/02hZl.png" alt="enter image description here"></p>
  
  <p>Problem: How can i set the placeholder height inside the fragments view to the header height inside the activity view?</p>
  
  <p>I want to create a custom view for the placeholder which find the header view from the activity and set its height to the height of the header.</p>
  
  <p>I want a solution for the view-layer but it know that i can use the OnGlobalLayoutListener or OnPredrawListener on activity/fragment-layer.</p>
  
  <p>In a nutshell: How can i access views from a custom view of the hole activity?</p>