About Notification Messages
HTML Help notification messages are sent from a help window to the window that you specify in an HtmlHelp() call. Use notification messages to track a user's activities in a help window. For example, if you want to invoke an action when a user clicks the Refresh button on the toolbar, you could use the HHN_TRACK message.
Notification messages occur for the following events:
- When a user clicks a button on the toolbar or clicks a tab on the Navigation pane of the HTML Help Viewer, an HHN_TRACK message is sent that identifies the button or tab that was clicked.
- When a user navigates to a topic, an HHN_NAVCOMPLETE message is sent that identifies the topic navigated to.
- When a help window is created, an HHN_WINDOW_CREATE message is sent that identifies the window being created.
To enable notification message tracking
HTML Help sends notification messages from help windows that have the following HH_WINTYPE property settings:
- The value of hwndCaller must be non zero.
- The value of idNotify must be non zero.
- A value must be specified for HHWIN_PARAM_PROPERTIES in the fsValidProperties member.
- A value must be specified for HHWIN_PROP_TRACKING in the fsWinProperties member.
To specify the window that will receive notification messages
Notification messages are sent to the window specified in the hwndCaller parameter of the HtmlHelp() call.
HTML Help notification messages are sent via Windows WM_NOTIFY messages.
Note
- Notification messages are not sent if the value of hwndCaller is the desktop.
Notification messages quick reference
