title: Check overwrite in File Save dialog in WxPython
body: <p>I need to check if the same file exists when I try to save a file in File Save Dialog. İf it does,
  it shouldnt allow me to do it and force me to change the name. How can I do this in WxPython?</p>
  
  <p>Thanks in advance.</p>
  
  <p>Here is my save code:</p>
  
  <pre><code>        #Dosya tipi filtreleri
          wildcard = "BENGI files (*.bengi)|*.bengi|"    \
         "SQLITE file (*.sdb)|*.sdb|"        \
         "All files (*.*)|*.*"
  
          dlg = wx.FileDialog(
              self, message="Save file as ...", defaultDir=DesktopPath, 
              defaultFile="_nokta_listesi", wildcard=wildcard, style=wx.SAVE
              )
  
  
          # Varsayılan dosya tipi filtresi
          dlg.SetFilterIndex(0)
  
          # Show the dialog and retrieve the user response. If it is the OK response, 
          # process the data.
          if dlg.ShowModal() == wx.ID_OK:
              path = dlg.GetPath()
  
              # Create a database in disk
              con=apsw.Connection(path)
  
              # Copy from memory to disk
              with con.backup("main", self.conn2, "main") as backup:
                  backup.step() # copy whole database in one go
  
              con.close(True) 
          dlg.Destroy()
  </code></pre>