WM_COMPAREITEM
Version 3.0
This message determines the relative position of a new item in a sorted owner-draw combo or list box.
Whenever the application adds a new item, Windows sends this message to the owner of a combo or list box created with the CBS_SORT or LBS_SORT style. The lParam parameter of the message is a long pointer to a COMPAREITEMSTRUCT data structure that contains the identifiers and application-supplied data for two items in the combo or list box. When the owner receives the message, the owner returns a value indicating which of the items should appear before the other. Typically, Windows sends this message several times until it determines the exact position for the new item.
wParam
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Is not used.
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lParam
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Contains a long pointer to a COMPAREITEMSTRUCT data structure that contains the identifiers and application-supplied data for two items in the combo or list box.
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Return Value
The return value indicates the relative position of the two items. It may be any of the following values:
–1
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Item 1 sorts before item 2.
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0
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Item 1 and item 2 sort the same.
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1
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Item 1 sorts after item 2.
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