An application sends an LB_SETCOUNT message to set the count of items in a list box created with the LBS_NODATA style and not created with the LBS_HASSTRINGS style.
LB_SETCOUNT wParam = (WPARAM) (int) cItems; // count of list box items lParam = 0; // not used; must be zero
Windows 95: The wParam parameter is limited to 16-bit values. This means list boxes cannot contain more than 32,767 items. Although the number of items is restricted, the total size in bytes of the items in a listbox is limited only by available memory.
If an error occurs, the return value is LB_ERR. If there is insufficient memory to store the items, the return value is LB_ERRSPACE.
The LB_SETCOUNT message is supported only by list boxes created with the LBS_NODATA style and not created with the LBS_HASSTRINGS style. All other list boxes return LB_ERR.