The PSM_APPLY message simulates the choice of the Apply Now button, indicating that one or more pages have changed and the changes need to be validated and recorded. The property sheet sends the PSN_KILLACTIVE notification message to the current page. If the current page returns FALSE, the property sheet sends the PSN_APPLY notification message to all pages. You can send the PSM_APPLY message explicitly or by using the PropSheet_Apply macro.
PSM_APPLY wParam = 0; lParam = 0;
Returns TRUE if all pages successfully applied the changes or FALSE otherwise.