NSSavePanel (and NSOpenPanel, as a subclass) supports a `message` (via `setMessage:message` in Obj-C), which allows a message to be displayed even when the panel is attached to a parent. Right now, `title` is useless for attached dialogs.

atom/browser/ui/file_dialog.h
#ifndef ATOM_BROWSER_UI_FILE_DIALOG_H_
#define ATOM_BROWSER_UI_FILE_DIALOG_H_
#include <string>
#include <utility>
#include <vector>
#include "base/callback_forward.h"
#include "base/files/file_path.h"
namespace atom {
class NativeWindow;
}
namespace file_dialog {
typedef std::pair<std::string, std::vector<std::string> > Filter;
typedef std::vector<Filter> Filters;
enum FileDialogProperty {