title: WPF How change a property in a page from another?
body: <p>I would like to change the property Visible of a control in the PAGE1 when I click on a button  on the PAGE2. The PAGE2 is a Pop'Up window with a message for the user. I want when he clicks on a button below that the property Visible from a control in the PAGE2 (still displayed in the background at the same time) change.</p>
  
  <p>The problem for me is that the event of my button belongs to the PAGE2 class and I'm not able to reach PAGE1's objects from there.</p>