Shell_NotifyIconA function (shellapi.h)

Sends a message to the taskbar's status area.

BOOL Shell_NotifyIconA(
  [in] DWORD            dwMessage,
  [in] PNOTIFYICONDATAA lpData
);

[in] dwMessage

Type: DWORD

A value that specifies the action to be taken by this function. It can have one of the following values:

0x00000000. Adds an icon to the status area. The icon is given an identifier in the NOTIFYICONDATA structure pointed to by lpdata—either through its uID or guidItem member. This identifier is used in subsequent calls to Shell_NotifyIcon to perform later actions on the icon.

0x00000001. Modifies an icon in the status area. NOTIFYICONDATA structure pointed to by lpdata uses the ID originally assigned to the icon when it was added to the notification area (NIM_ADD) to identify the icon to be modified.

0x00000002. Deletes an icon from the status area. NOTIFYICONDATA structure pointed to by lpdata uses the ID originally assigned to the icon when it was added to the notification area (NIM_ADD) to identify the icon to be deleted.

0x00000003. Shell32.dll version 5.0 and later only. Returns focus to the taskbar notification area. Notification area icons should use this message when they have completed their UI operation. For example, if the icon displays a shortcut menu, but the user presses ESC to cancel it, use NIM_SETFOCUS to return focus to the notification area.

0x00000004. Shell32.dll version 5.0 and later only. Instructs the notification area to behave according to the version number specified in the uVersion member of the structure pointed to by lpdata. The version number specifies which members are recognized.

NIM_SETVERSION must be called every time a notification area icon is added (NIM_ADD). It does not need to be called with NIM_MODIFY. The version setting is not persisted once a user logs off.

For details, see the Remarks section.

[in] lpData

Type: PNOTIFYICONDATA

A pointer to a NOTIFYICONDATA structure. The content of the structure depends on the value of dwMessage. It can define an icon to add to the notification area, cause that icon to display a notification, or identify an icon to modify or delete.

Type: BOOL

Returns TRUE if successful, or FALSE otherwise. If dwMessage is set to NIM_SETVERSION, the function returns TRUE if the version was successfully changed, or FALSE if the requested version is not supported.

As of Windows 2000 (Shell32.dll version 5.0), if you set the uVersion member of the NOTIFYICONDATA structure pointed to by lpdata to NOTIFYICON_VERSION_4 or higher, Shell_NotifyIcon mouse and keyboard events are handled differently than in earlier versions of Windows. The differences include the following:

• If a user selects a notify icon's shortcut menu with the keyboard, the Shell now sends the associated application a WM_CONTEXTMENU message. Earlier versions send WM_RBUTTONDOWN and WM_RBUTTONUP messages.
• If a user selects a notify icon with the keyboard and activates it with the SPACEBAR or ENTER key, the version 5.0 Shell sends the associated application an NIN_KEYSELECT notification. Earlier versions send WM_RBUTTONDOWN and WM_RBUTTONUP messages.
• If a user selects a notify icon with the mouse and activates it with the ENTER key, the Shell now sends the associated application an NIN_SELECT notification. Earlier versions send WM_RBUTTONDOWN and WM_RBUTTONUP messages.

As of Windows XP (Shell32.dll version 6.0), if a user passes the mouse pointer over an icon with which a balloon notification is associated, the Shell sends the following messages:

• NIN_BALLOONSHOW. Sent when the balloon is shown (balloons are queued).
• NIN_BALLOONHIDE. Sent when the balloon disappears. For example, when the icon is deleted. This message is not sent if the balloon is dismissed because of a timeout or if the user clicks the mouse.

  As of Windows 7, NIN_BALLOONHIDE is also sent when a notification with the NIIF_RESPECT_QUIET_TIME flag set attempts to display during quiet time (a user's first hour on a new computer). In that case, the balloon is never displayed at all.

• NIN_BALLOONTIMEOUT. Sent when the balloon is dismissed because of a timeout.
• NIN_BALLOONUSERCLICK. Sent when the balloon is dismissed because the user clicked the mouse.

In addition to those messages, as of Windows Vista (Shell32.dll version 6.0.6), if a user passes the mouse pointer over an icon with which a balloon notification is associated, the Windows Vista Shell also adds the following messages:

• NIN_POPUPOPEN. Sent when the user hovers the cursor over an icon to indicate that the richer pop-up UI should be used in place of a standard textual tooltip.
• NIN_POPUPCLOSE. Sent when a cursor no longer hovers over an icon to indicate that the rich pop-up UI should be closed.

Regardless of the operating system version, you can select which way the Shell should behave by calling Shell_NotifyIcon with dwMessage set to NIM_SETVERSION. Set the uVersion member of the NOTIFYICONDATA structure pointed to by lpdata to indicate whether you want Windows 2000, Windows Vista, or pre-version 5.0 (Windows 95) behavior. As of Windows XP Service Pack 2 (SP2), a custom icon can be displayed in the notification balloon. This allows the calling process to customize the notification beyond the previously available options of info, warning, and error, and distinguish it from other types of notification for the user.

Notifications and the Notification Area