When the user selects a tab, a tab control sends notification messages to its parent window in the form of WM_NOTIFY messages. The tab control sends the TCN_SELCHANGING notification message before the selection changes, and it sends the TCN_SELCHANGE notification message after the selection changes.
You can process TCN_SELCHANGING to save the state of the outgoing page. You can return TRUE to prevent the selection from changing. For example, you might not want to switch away from a child dialog box in which a control has an invalid setting.
To display the incoming page in the display area, you must process TCN_SELCHANGE. Though processing might entail changing the information displayed in a child window, it will more likely entail destroying or hiding the outgoing child window or dialog box and creating or showing the incoming child window or dialog box.
You can retrieve and set the current table selection by using the TCM_GETCURSEL and TCM_SETCURSEL messages.