This message is sent to the owner of a list box that has a style of LS_OWNERDRAW, to offer the owner an opportunity to establish the height and width (for a horizontally scrollable list box control) of an item that accommodates any special requirements for the drawing of items in that list box. It is sent when items in the list box are inserted or deleted, and also when presentation parameters for the list box change.

All items in a list box must have the same height, which must be greater than or equal to the height of the current font.

In particular, this notification is sent to the owner of a list box that has a style of LS_OWNERDRAW, to offer the owner an opportunity to establish the height and width (for a horizontally scrollable list box control) of an item that accommodates any special requirements for the drawing of items in that list box.