title: AspxClientPopupControl: CloseButtonClick and ValueChanged
body: <p>I am using DevExpress v10. I have an ASP.NET page with AspxPopupControl. The AspxPopupControl contains several textboxes AspxTextBox.</p>
  
  <p>I need the following functionality: when user clicks Close button in header of the AspxPopupControl popup, to check if something has been changed in the AspxTextBox fields since the popup was opened. If it has, a confirmation 'do you really want to close the window without saving?'</p>
  
  <p>I intended to implement it as the following: to handle client-side event ValueChanged for the AspxClientTextBox controls. In such handler I could set a flag, and later analyze it in client-side handler of Closing event (AspxClientPopupControl)</p>
  
  <p>But the problem is: if I change something in an AspxTextBox and then click the Close button immediately, Closing event will be fired FIRST and ValueChanged event will be fired AFTER Closing!</p>
  
  <p>This does not allow me to do what I want.</p>
  
  <p>Is any solution possible here?</p>