title: In electron, BrowserWindow.getFocusedWindow returns null when invoked from dialog.showSaveDialog
body: <p>In electron, is there a way to get the current focused window during a call to <code>dialog.showSaveDialog</code>? This works fine from within <code>dialog.showOpenDialog</code> but returns <code>null</code> when done from within <code>dialog.showSaveDialog</code>.</p>
  
  <p>This works:</p>
  
  <pre><code>  dialog.showOpenDialog(function (filepaths) {
      if(filepaths !== undefined){
        BrowserWindow.getFocusedWindow().send('file-open', filepaths[0])
      }
    });
  </code></pre>
  
  <p>This throws <code>TypeError: Cannot read property 'send' of null</code>:</p>
  
  <pre><code>dialog.showSaveDialog(options, function (filepath) {
    if (filepath !== undefined) {
      BrowserWindow.getFocusedWindow().send('file-save', filepath)
    }
  }); 
  </code></pre>