Checked and Unchecked Menu Items

A menu item can be either checked or unchecked. Windows displays a bitmap next to checked menu items to indicate their checked state. Windows does not display a bitmap next to unchecked items, unless an application-defined "unchecked" bitmap is specified. Only menu items in a menu can be checked; items in a menu bar cannot be checked.

Applications typically check or uncheck a menu item to indicate whether an option is in effect. For example, suppose an application has a toolbar that the user can show or hide by using a Toolbar command on a menu. When the toolbar is hidden, the Toolbar menu item is unchecked. When the user chooses the command, the application checks the menu item and shows the toolbar.

A check-mark attribute controls whether a menu item is checked. You can set a menu item's check-mark attribute by using the CheckMenuItem function. You can use the GetMenuState function to determine whether a menu item is currently checked or unchecked.

Instead of CheckMenuItem and GetMenuState, you can use the GetMenuItemInfo and SetMenuItemInfo functions to retrieve and set the check state of a menu item.

Sometimes, a group of menu items corresponds to a set of mutually exclusive options. In this case, you can indicate the selected option by using a checked radio menu item (analogous to a radio button control). Checked radio items are displayed with a bullet bitmap instead of a check-mark bitmap. To check a menu item and make it a radio item, use the CheckMenuRadioItem function.

By default, Windows displays a check-mark or bullet bitmap next to checked menu items and no bitmap next to unchecked menu items. However, you can use the SetMenuItemBitmaps function to associate application-defined checked and unchecked bitmaps with a menu item. Windows then uses the specified bitmaps to indicate the menu item's checked or unchecked state.

Application-defined bitmaps associated with a menu item must be the same size as the default check-mark bitmap, the dimensions of which may vary depending on screen resolution. To retrieve the correct dimensions, use the GetMenuCheckMarkDimensions function. You can create multiple bitmap resources for different screen resolutions; create one bitmap resource and scale it, if necessary; or create a bitmap at run time and draw an image in it. The bitmaps may be either monochrome or color. However, because menu items are inverted when highlighted, the appearance of certain inverted color bitmaps may be undesirable. For more information, see Bitmaps.