How To Expose Owner-drawn List Boxes by Active Accessibility

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• If you use the LBS_SORT style, the list box is sorted using the supplied strings and not the WM_COMPAREITEM callback.
• With owner-drawn variable lists, you should use a global variable or some other mechanism to keep track of when the itemdata member of the MEASUREITEMSTRUCT is valid. You need the global variable because Windows sends the WM_MEASUREITEM message as soon as the string is added, but before the item data has been attached. At this point, the itemdata member of the MEASUREITEMSTRUCT is not valid.
• Additional precautions are required if you use advanced owner-draw methods such as changing the names of items or rearranging the items. One example is the old technique of using an owner-drawn list box to create a control that collapses and expands like a tree view control. List boxes do not allow you to change item strings. Therefore, to obtain the same result, you must delete the item and insert it with the new string name.