QMenuBar Class

The QMenuBar class provides a horizontal menu bar. More...

Header:	#include <QMenuBar>
qmake:	QT += widgets
Inherits:	QWidget

List of all members, including inherited members

Properties

defaultUp : bool
nativeMenuBar : bool

Public Functions

bool	isDefaultUp() const
bool	isNativeMenuBar() const
void	setDefaultUp(bool)
void	setNativeMenuBar(bool nativeMenuBar)

Detailed Description

A menu bar consists of a list of pull-down menu items. You add menu items with addMenu(). For example, assuming that menubar is a pointer to a QMenuBar and fileMenu is a pointer to a QMenu, the following statement inserts the menu into the menu bar:

 menubar->addMenu(fileMenu);

The ampersand in the menu item's text sets Alt+F as a shortcut for this menu. (You can use "&&" to get a real ampersand in the menu bar.)

There is no need to lay out a menu bar. It automatically sets its own geometry to the top of the parent widget and changes it appropriately whenever the parent is resized.

Usage

In most main window style applications you would use the menuBar() function provided in QMainWindow, adding QMenus to the menu bar and adding QActions to the pop-up menus.

Example (from the Menus example):

     fileMenu = menuBar()->addMenu(tr("&File"));
     fileMenu->addAction(newAct);

Menu items may be removed with removeAction().

Widgets can be added to menus by using instances of the QWidgetAction class to hold them. These actions can then be inserted into menus in the usual way; see the QMenu documentation for more details.

Platform Dependent Look and Feel

Different platforms have different requirements for the appearance of menu bars and their behavior when the user interacts with them. For example, Windows systems are often configured so that the underlined character mnemonics that indicate keyboard shortcuts for items in the menu bar are only shown when the Alt key is pressed.

On macOS and on certain Linux desktop environments such as Ubuntu Unity, QMenuBar is a wrapper for using the system-wide menu bar. If you have multiple menu bars in one dialog the outermost menu bar (normally inside a widget with widget flag Qt::Window) will be used for the system-wide menu bar.

Qt for macOS also provides a menu bar merging feature to make QMenuBar conform more closely to accepted macOS menu bar layout. The merging functionality is based on string matching the title of a QMenu entry. These strings are translated (using QObject::tr()) in the "QMenuBar" context. If an entry is moved its slots will still fire as if it was in the original place. The table below outlines the strings looked for and where the entry is placed if matched:

String matches	Placement	Notes
about.*	Application Menu \| About <application name>	The application name is fetched from the `Info.plist` file (see note below). If this entry is not found no About item will appear in the Application Menu.
config, options, setup, settings or preferences	Application Menu \| Preferences	If this entry is not found the Settings item will be disabled
quit or exit	Application Menu \| Quit <application name>	If this entry is not found a default Quit item will be created to call QCoreApplication::quit()

You can override this behavior by using the QAction::menuRole() property.

If you want all windows in a Mac application to share one menu bar, you must create a menu bar that does not have a parent. Create a parent-less menu bar this way:

 QMenuBar *menuBar = new QMenuBar(nullptr);

Note: Do not call QMainWindow::menuBar() to create the shared menu bar, because that menu bar will have the QMainWindow as its parent. That menu bar would only be displayed for the parent QMainWindow.

Note: The text used for the application name in the macOS menu bar is obtained from the value set in the Info.plist file in the application's bundle. See Qt for macOS - Deployment for more information.

Note: On Linux, if the com.canonical.AppMenu.Registrar service is available on the D-Bus session bus, then Qt will communicate with it to install the application's menus into the global menu bar, as described.

Examples

The Menus example shows how to use QMenuBar and QMenu. The other main window application examples also provide menus using these classes.

Property Documentation

defaultUp : bool

This property holds the popup orientation

The default popup orientation. By default, menus pop "down" the screen. By setting the property to true, the menu will pop "up". You might call this for menus that are below the document to which they refer.

If the menu would not fit on the screen, the other direction is used automatically.

Access functions:

bool	isDefaultUp() const
void	setDefaultUp(bool)

nativeMenuBar : bool

This property holds whether or not a menubar will be used as a native menubar on platforms that support it

This property specifies whether or not the menubar should be used as a native menubar on platforms that support it. The currently supported platforms are macOS, and Linux desktops which use the com.canonical.dbusmenu D-Bus interface (such as Ubuntu Unity). If this property is true, the menubar is used in the native menubar and is not in the window of its parent; if false the menubar remains in the window. On other platforms, setting this attribute has no effect, and reading this attribute will always return false.

The default is to follow whether the Qt::AA_DontUseNativeMenuBar attribute is set for the application. Explicitly setting this property overrides the presence (or absence) of the attribute.

This property was introduced in Qt 4.6.