- Electron version: 1.1.0
- Operating system: N/A

Currently there isn't any way to remove dialog boxes (such as ones created through `dialog.showMessageBox`).  This can be useful in, for example, "Keep Waiting" dialogs.  After the window becomes responsive again it would be great if we could programmatically close the dialog.

shell/browser/ui/message_box_gtk.cc
parent_->RemoveObserver(this);
    parent_ = nullptr;
  }
  CHROMEG_CALLBACK_1(GtkMessageBox, void, OnResponseDialog, GtkWidget*, int);
  CHROMEG_CALLBACK_0(GtkMessageBox, void, OnCheckboxToggled, GtkWidget*);
 private:
  electron::UnresponsiveSuppressor unresponsive_suppressor_;
  
  int cancel_id_ = 0;
  bool checkbox_checked_ = false;
  NativeWindow* parent_;
  GtkWidget* dialog_;
  MessageBoxCallback callback_;
  DISALLOW_COPY_AND_ASSIGN(GtkMessageBox);
};
void GtkMessageBox::OnResponseDialog(GtkWidget* widget, int response) {
  gtk_widget_hide(dialog_);
  if (response < 0)
    std::move(callback_).Run(cancel_id_, checkbox_checked_);
  else
    std::move(callback_).Run(response, checkbox_checked_);
  delete this;
}
void GtkMessageBox::OnCheckboxToggled(GtkWidget* widget) {