title: How to read/write in a parent frame's variable in UWP?
body: <p>In my MainPage.xaml I've got a SplitView that loads many pages inside a frame created in it's SlplitView.Content.</p>
  
  <p>I've got data in a MainPage's variable that needs to be sent to every page that loads in my SplitView content's frame according to the ListBoxItem clicked.</p>
  
  <p>Also in the current page I may have to update the MainPage's variable before a new page is loaded.</p>
  
  <p>How can I do this? Is there a way to declare a global variable? Can I transport that information from a page to another updating it's value on the parent page?</p>