| Name | Type | Defined Value |
| None | Not occurs | WSEV_NONE |
| INITIALIZE | When the instance is initilized. | WSEV_INITIALIZE |
| DELETE | When the instance is released. | WSEV_DELETE |
| ACTIVATE | When the instance is activated. | WSEV_ACTIVATE |
| VALUE-CH | When the value is changed. | WSEV_VALUE_CH |
| VISIBLE-CH | When the WSNvis property is changed. | WSEV_VISIBLE_CH |
| PARENT-VISIBLE-CH | When the visible property of the parent instance is changed. | WSEV_PARENT_VISIBLE_CH |
| EXPOSE | When the instance is exposed. | WSEV_EXPOSE |
| MOUSE-IN | When the mouse pointer comes into the area | WSEV_MOUSE_IN |
| MOUSE-OUT | When the mouse pointer goes out of the area. | WSEV_MOUSE_OUT |
| BEGIN | When the scroll bar moves to initial position. | WSEV_BEGIN |
| END | When the scroll bar moves to end position. | WSEV_END |
| INCREMENT | When the value is increased. | WSEV_INCREMENT |
| DECREMENT | When the value is decreased. | WSEV_DECREMENT |
| PAGE-INCREMENT | When the value is increased by a page. | WSEV_PAGE_INCREMENT |
| PAGE-DECREMENT | When the value is decreased by a page. | WSEV_PAGE_DECREMENT |