- Electron version: 1.2.2
- Operating system: Linux

This is a problem only in linux. It works in OSX.

``` javascript
win.hide()
win.capturePage(function(img){
 // never called
})
```

shell/browser/api/electron_api_web_contents.cc
.ThrowError("webContents.print(): Invalid print settings specified.");
    return;
  }
  printing::CompletionCallback callback;
  if (args->Length() == 2 && !args->GetNext(&callback)) {
    gin_helper::ErrorThrower(args->isolate())
        .ThrowError("webContents.print(): Invalid optional callback provided.");
    return;
  }
   Set optional silent printing
  bool silent = false;
  options.Get("silent", &silent);
  bool print_background = false;
  options.Get("printBackground", &print_background);
  settings.SetBoolKey(printing::kSettingShouldPrintBackgrounds,
                      print_background);
   Set custom margin settings
  gin_helper::Dictionary margins =
      gin::Dictionary::CreateEmpty(args->isolate());
  if (options.Get("margins", &margins)) {
    printing::mojom::MarginType margin_type =
        printing::mojom::MarginType::kDefaultMargins;
    margins.Get("marginType", &margin_type);
    settings.SetIntKey(printing::kSettingMarginsType,
                       static_cast<int>(margin_type));
    if (margin_type == printing::mojom::MarginType::kCustomMargins) {
      base::Value custom_margins(base::Value::Type::DICTIONARY);
      int top = 0;
      margins.Get("top", &top);
      custom_margins.SetIntKey(printing::kSettingMarginTop, top);