title: how to pass data from one window to another?
body: <p>I am working on C# wpf, and I am trying to create 'favorite' function on it.
  There is one window called 'favorite' and it is where a user can save his data.
  Another window is 'MainWindow' and I want to load the data here.</p>
  
  <p>There are two buttons and two textbox in 'favorite'.
  If I type words in each box, I hope they can be saved if I click star1button.
  And if I type another words in each box, I hope they would be saved if I click star2button. 
  So I hope each data will be stored separately, without being overlapped.</p>
  
  <p>And then, if I press button1 on 'mainwindow', I hope those words of star1button would show up in textboxes of mainwindow. 
  And if I press button2 on mainwindow, I hope words of star2button would show up in textboxes of mainwindow. </p>
  
  <p>Thanks in advance!!</p>