title: Mainwindow.xaml can not design when open but still drop item from toolbox
body: <p>Somethings  went  wrong  when  I open <code>Mainwindow.xaml</code>.I couldn't  drag, move or  edit control(<code>button, textbox</code>,.....).</p>
  
  <p><a href="https://i.stack.imgur.com/meSnT.png" rel="nofollow noreferrer">Click to see my error</a></p>
  
  <p>This is what I try to fix it:</p>
  
  <p>•I try to edit by coding, every controls in <code>designing form</code> still were changed when I edited by code but could not move or edit by designing</p>
  
  <p>•I also try to drag some controls from toolbox to <code>designing form</code>  and it work correctly(every controls could move or edit by designing) but controls appear before still perform.</p>
  
  <p>•Try open <code>Mainwindow.xaml</code> by <code>Blend Visua Studio</code></p>
  
  <p>I'm using <code>WPF</code>, Design by  <code>Ribbon- Control</code></p>
  
  <p>THANKS!</p>